Shortly after the Los Angeles Angels designated surefire future Hall of Famer Albert Pujols for assignment on May 6, MLB analyst and author Ryan M. Spaeder tweeted a stat that seemed momentarily impossible. Pujols, Spaeder noted, had recorded a hit off 10.21 percent of all players to throw a pitch in big-league history.

Like so much that happens on Twitter, the original missive was met by forceful -- if unsubstantiated and incorrect -- pushback, as well as a couple of "Anchorman" memes. But the math checked out, as did the general point. Pujols, who debuted in 2001, had, as of that day, faced 1,630 pitchers in his 2,886 big-league games, meaning he saw, on average, .56 unique hurlers per game in his career. To put that in perspective, looking at some of baseball-reference.com’s comps for his most similar players, Ken Griffey Jr. (1989–2010) saw .50 unique pitchers per game. Rafael Palmeiro (1986–2005) saw .42. And for Eddie Murray (1977–97), the number was just .35. The game is quickly changing, that much is obvious.

Relief pitchers are throwing more than ever, which means that hitters have that much more on their minds. The Hall of Fame is littered with sluggers who feasted on mistakes from tired pitchers, but today’s batters are lucky to see a guy more than twice in a game (and when they do, it’s usually because that day’s starter is on some kind of roll).

So as the 2021 Yankees endured and then emerged from an early season funk, it was on the heels of their bullpen. The motley crew might not all be household names to casual observers, yet the late-inning arms proved downright essential as a stabilizing force during an up-and-down start to 2021.

“I’ve always wanted to have a bullpen kind of like we have now,” says Mike Harkey, who has coached Yankees relievers for 12 seasons and has seen the job evolve to include almost as much focus on openers as closers. Every day, Harkey -- along with manager Aaron Boone, pitching coach Matt Blake and the dozen or so less-prominent but still integral voices in the Yankees’ braintrust -- tries to pave a road from that day’s starter through closer Aroldis Chapman. The recipe includes its share of (Chad) Greens, along with special ingredients such as a Loaisiga here, an O’Day there and a pinch of Wilson.

Harkey has more cooks in the kitchen than ever before, and more raw materials as well. But the final product has never been better.

“Ultimately,” Blake says of his relievers, “they’re going out and competing with their best stuff on a nightly basis. We’re lucky to have a lot of really talented pitchers, and we’re hopefully putting them in good situations, and they’re executing.”

• • •

Like any good bullpen, this story might as well lead with the end, with the superhuman display fans hope to see every ninth inning. For two decades, fans marveled at Mariano Rivera’s voodoo, his ability to claim total control of opponents' bats and brains with just one pitch. Hitters knew what was coming, they just couldn’t hit it. And at a position that is as volatile as any in sports, there was Rivera, year after year after year ...

For Chapman, the formula is different. When it came to Rivera, you always wondered why no one could adjust to his one pitch; with Chapman, you wonder how anyone ever gets a hit. The Cuban defector isn’t throwing 104 mph anymore (although his velocity is noticeably up this year), but his combination of a top-tier fastball and a wipeout slider has long made him nearly impossible to face. And after toying with a splitter in bullpens and warmups for years (and very occasionally throwing it in a game), he’s using the pitch at nearly a 15 percent clip in 2021.

“It goes back to when I started pitching,” Chapman says, assisted by Yankees bilingual media relations coordinator Marlon Abreu. He tries to model his split-fingered offering after what he long admired in another Cuban pitcher, José Contreras.

“When I was playing for the Cincinnati Reds, I guess they didn’t like me throwing that pitch, maybe because I was younger and they felt that it was unnecessary, or not a tool at the time. But I’ve always liked using the pitch, and after practicing with it, going back to last season and playing catch and getting back in the habit of using and throwing the pitch, it’s there for me now.”

Sometimes baseball needs to be explained in terms of process; a pitcher can do everything right, yet get tagged for a bunch of seeing-eye singles or get burned by defensive positioning. For Chapman, though, the evolving process -- to say nothing of the work that the jacked pitcher puts in to keep his body in better than tip-top shape -- is perfectly evident in the results. Over his first 13 innings in 2021, his only blemish was a solitary unearned run, which came in extra innings, with a runner starting on second base. Meanwhile, he was throwing more strikes than ever, with approximately 72 percent of his offerings going in the good column (and it wasn’t just a matter of forcing hitters to chase; his 63 percent zone percentage was by far the highest figure of his career). Chapman was forcing hitters to attack his unhittable pitches, then shaking hands with his teammates after sealing the deal yet again. “Overall just commanding the zone and controlling the strike zone has been the key for me,” Chapman says.

Harkey sees Chapman’s success, and he notes how it trickles down to the team’s other relievers. The Yankees’ closer has been so dominant in the highest-leverage situations that it, in turn, lowers the temperature for the rest of the game. But it all begins (or really ends) with the closer.

“We have six, seven, eight guys that can get high-leverage outs in a game,” Harkey says. “That’s huge. But we also have guys that have roles that play better in lower-leverage games or guys that play better in medium-leverage games. But one of the things I’ve always been really lucky with -- or the Yankees have been really lucky with -- in my 12 years here is they’ve always had a guy that can get the last three outs of the game, which, in my opinion, are the hardest three outs to get in any game. I had Mo for [six] years. I had Andrew Miller, I had Rafael Soriano. I had Dave Robertson. And now I’ve got Chap. So you can’t put a value on how important that is to developing young up-and-coming pitchers.”

• • •

Back in the old days, going to the bullpen meant summoning a fresh arm, a less tired option for the rare occasion when your starter wasn’t going to complete all nine innings. Almost without exception, the manager was bringing in a lesser pitcher, a guy who couldn’t cut it as a starter for whatever reason. Today’s Yankees bullpen is still filled with pitchers who began their careers in the first inning, but for a number of different reasons are now shutting down opposing hitters one late inning at a time. And when Boone signals for a replacement, it’s with a ton of precise data. Of course, the old-school ideal of attacking left-right splits still applies, even with MLB’s new rule that forces relievers to throw to at least three batters (or through the end of an inning). But Boone also can consult reams of data to see which batters, perhaps, fare terribly against sliders in night games, or other less absurd splits. So, when Corey Kluber and his consistent three-quarters release point departs the game for Darren O'Day -- a throwback sidearmer -- a hitter has to adjust to a totally different arm angle, to say nothing of a change in arsenal.

Lucas Luetge’s cutter plays off Jonathan Loaisiga’s two-seamer, which differs from Chad Green’s high four-seam action. Neither O’Day nor Wandy Peralta nor Luis Cessa throws a fastball more than half the time, but hitters would never suggest that at-bats against the three pitchers are in any way similar.

“The variety of arms has kind of come in vogue here in the last few years,” O’Day says. “We have all kinds of supercomputers and nerds in the background that have spit out these sheets of, ‘Which one of these variety of arm angles and pitch characteristics are going to work against certain hitters?’ So I think teams are trying to diversify a little bit with that because, for a few years there, we got too dependent on the high-spin four-seam and the breaking ball in the dirt, and hitters started seeing it every single day. They’ve adjusted to be able to hit that a little bit more, and the trend is kind of swinging back to more variety.”

“It’s nice to have different looks out there just for the sake of not having the same type of guy over and over again,” Blake adds. “It’s also just how we match up with different hitters at different points in the game to give us a couple different opportunities to give different looks, and also find the best matchups for all these guys. If there’s nine hitters in the lineup, there might be three or four different types of hitters that you’re really looking at. And then that allows us to look at, ‘OK, what lane or avenue is the best spot to put this reliever in, in this part of the game based on his skill set or his pitch mix or his release point?’ But also, ‘What’s he ready to handle?’”

With starters, Blake and Boone are trying to find guys who can diversify their repertoires and maintain a high level several times through the order. But Harkey hopes to keep things a bit simpler. Chapman’s new splitter aside, the bullpen coach wants to see his pitchers hone two dominant pitches, the better to maintain the weapons’ precision. “It’s just so much easier,” Harkey says.

For Loaisiga, the early years in the starting rotation showed incalculable potential, but the pitcher never could put a bow on the package. This year, though, with an added reliance on the two-seam fastball -- he has basically reversed its usage and that of his four-seamer from previous years, plus he’s incorporating a changeup a bit more -- Loaisiga is pitching like an elite reliever. His walks are way down, and his strikeout percentage remains impressive. Through the Yankees’ first homestand in May, his FIP- -- a neutralized stat that measures a pitcher’s success without accounting for fielding or other factors out of his control -- was 79, 21 percent better than the league average.

“You knew it was only a matter of time before he was going to be able to harness his stuff,” Green says of the Nicaraguan reliever. “And I think he’s really taken on being in the bullpen and attacking guys and kind of letting it go for an inning or two.”

Loaisiga sees another difference, one that teammates such as Green have helped him build.

“Confidence,” the 26-year-old says. “It’s key. The experience of being there, having the opportunity to talk to my teammates and listen to their pointers. And above all, staying aggressive, staying away from walks and trying to attack hitters.”

Beyond temperament, though, what makes Loaisiga successful is light years different from what a pitcher such as Green deploys in games. The veteran right-hander -- another guy who spent his first years in the bullpen dreaming of starting before his success late in games made him too valuable to move -- works high in the zone with a four-seamer that relies on a high spin rate to stay elevated. In a sense, while pitchers such as Chapman and Zack Britton are performing ridiculous feats with the baseball, making their offerings move in ways difficult to see, let alone hit, Green is challenging batters to connect with balls that should be reasonably hittable. A high fastball? Seems like a dream for a big-league hitter. But year after year, Green laughs last.

In 2021, the 30-year-old has offered fastballs and curves at about a 65/35 split, but his consistent delivery, as well as the tireless behind-the-scenes work, has seen him once again getting positive results. “He doesn’t walk a lot of guys, and most of the time he’s able to get quick outs,” Harkey says of Green. “He reminds me probably the most of Mariano because of his ability to repeat a delivery and command one pitch a lot more than anybody else.

“I mean, he’s the same every single day. He works his tail off to be better. He’s always hungry for information.”

• • •

Gerrit Cole can give up a home run here or there and still have a great game. But when a reliever offers up an eighth-inning blast in a tight contest, it can be a disaster. Green offers the tried-and-true cliche that it’s important for relievers to have short memories. And when he badly missed a spot to Jose Altuve on May 6 and watched as the Astros' diminutive second baseman trotted around the basepaths, savoring a game-changing three-run homer that had totally shifted the energy at Yankee Stadium, it was important that he follow his own advice. Indeed, after the bullpen imploded for a second straight game the next night, it was easy to wonder if all this talk about the Yankees relievers’ impressive start had been premature.

But the Yankees won the next two games in walk-off fashion, boosted in no small part by a bullpen that combined to pitch eight innings, allowing just the one unearned tally in extras against Chapman. Overall, Nationals hitters earned just five hits and one walk in the eight frames, and the Yankees’ relievers struck out nine.

“I think the thing that you can count on with a lot of these guys is that they’re going to throw strikes,” Blake says, and the stats back him up. Through 34 games, the Yankees’ relievers enjoyed a 21.9 K-BB percentage (their relievers had recorded strikeouts in 30 percent of plate appearances, vs. the 8.1 percent that ended in walks). The figure was tops in the league by a solid margin, and if it holds, it would be the team’s best mark since at least 1916, the first year for which FanGraphs has the data available (and considering how much less prevalent strikeouts were before then, it would almost certainly be the best in team history). “I think the confidence we have in that group is, they can all take their turn in different areas on a given night, and they’re all going to be competitive and consistent in that regard,” Blake says.

Strike-throwing is a skill, one of many that the team’s coaches drilled into the pitchers during spring training sessions in Tampa’s “Gas Station.” The high-tech facility, with Rapsodo machines, high-speed cameras and all manner of other tools, was a fun curiosity for writers covering the proceedings in Florida, but early returns are promising.

“I think it accelerates development,” Harkey says. “And I think it offsets a lot of the time where you can help guys fix certain things, because we’re all visual people. If Matt Blake, [director of pitching] Sam Briend and all these guys started talking to me about all of the measurements and the numbers that come across these machines, I’d think they were speaking Spanish. But when they say it to me and I’m able to equate the numbers with the visual, it just makes it make more sense.”

Harkey is 54 years old; Blake turned 36 in May. “I’m old enough to be his dad,” Harkey quips. But he also notes that the two benefit each other. Blake can help make sense of some of the new-school analytics that the team (and the league) uses to create robust plans. And meanwhile, Harkey has the knowledge of a lifetime spent in dugouts and bullpens, and on big-league mounds. “Kind of turning a little bit of the new-school into the old-school explanation, which most people understand,” Harkey says of his impact. “I really hate to say, ‘Back when I did it, we did it like this,’ because it’s not back when I did it. Things are different. Guys throw harder, guys are bigger, guys are stronger than when I played.”

The challenges in 2021 are too numerous to mention. Pitchers are throwing harder than ever, putting their arms in peril. Meanwhile, they’re juggling more in formation than ever before, in order to win a showdown against a batter similarly armed with knowledge. And, of course, all of this is coming off a 60-game season in 2020, the impacts of which probably won’t be fully understandable for months if not years.

Justin Wilson was very effective for the Mets in 2020, but he threw just 19 2/3 innings, a mark he seemed bound to surpass before the official start of summer. Keeping the staff healthy and strong will be a yearlong task, and it will involve a lot of hard, occasionally unfair decisions. Michael King says that his mother allows him a 10-second pity party every time something doesn’t work out. And for King, “not working out” is a pretty complex idea thus far in 2021. He pitched three times in April, all in relief (including a remarkable six-inning outing on April 4, in which he allowed just one hit and one walk). After each appearance, the shortest of them being a two-inning stint on April 28, he was sent to the Yankees’ alternate site in Pennsylvania. His effective work, handling multiple innings out of the ’pen, meant that he would need to sit for a few days, and the Yankees needed available arms. If King was hoping to avoid the Scranton Shuttle, his success was working against him.

“I know that it’s not going to do me any good sitting and pouting and getting angry or sad,” King says. “So after those 10 seconds go away, I just say, ‘All right, let’s move forward,’ and the next time I get my opportunity, continue to make it a hard decision for them to send me down.”

Those hard decisions might cause some heartache, but that’s the business. “It’s the price that you pay,” Harkey says. “We had Loaisiga, who got sent up and down early in his career because he wasn’t ready. Chad Green, up and down because he wasn’t ready. Luis Cessa, up and down.

“So when you look at that, it’s just all a part of the development. And now we have the Nick Nelsons, the Mike Kings, the Deivi Garcías. In their development, they’re going to have to learn how to deal with a lot of disappointment and even disappointment that comes at the expense of success.”

• • •

Boone, Blake and Harkey are well-liked among Yankees players and, in turn, they like the guys they direct. Harkey couldn’t wait for Britton’s return, not just because the left-hander’s sinker is one of the best pitches in the game, but also because he spent the first few months of this season laughing nonstop at things he heard out of O’Day’s mouth, and he knows that O’Day and Britton ran a loose and fun bullpen together in Baltimore for years. Harkey believes in keeping his relievers relaxed -- and prepared.

“He knows all these hitters like the back of his hand,” King says. “He’s able to tell you exactly the holes that he wants you to expose. And he’s not afraid to tell you when you didn’t do that, like, ‘Hey, I told you to do this, and you did something else. And that’s why you got burned.’”

The road map to Chapman goes through a bunch of veteran starting pitchers and some relievers who have miles on their arms, but it also leans heavily on guys such as Loaisiga and fellow 26-year-old King, to say nothing of the roles that youngsters Nelson, García and others should continue to play over the years. The Yankees expect to see pitchers who continue to develop at the top level in the way that Loaisiga has, but every night on a Major League mound counts in the standings, and the results matter.

Fortunately, they’ve been mostly good so far. According to FanGraphs, the Yankees’ bullpen ranks either first or second in the American League in K/9, BB/9, K/BB, FIP- and WAR, to offer just a sampling of the accolades.

Boone is charged with signaling for a reliever, but then he can do little more than lean on the same optimism and hope as the fans in the stands. Fortunately, he sees a group that’s well built, well led, well trained and, at least so far, pitching incredibly well.

“I would say first and foremost, we’ve got really good pitchers, guys that are capable of going out there and performing,” Boone says. “And then I think Matt and Hark do a really good job of getting our guys ready, getting our guys prepared.

“Ultimately, what makes a good bullpen is not always just having a great closer and a couple great setup men, but you’re going to have to lean on Pitcher 6, 7, 8, 9, 10 down there in some big spots over the course of a year.”