In what's a relatively weak free-agent class for relievers, Wills Smith and Harris probably are the cream of the crop, and Smith already signed with Atlanta. Alternatively, you can gamble on a Dellin Betances rebound, but other than those names, Drew Pomeranz is the best reliever that you didn't know your team needed. If that's surprising, because he's been part of seven organizations since he was drafted by Cleveland in 2010, because he had a 4.85 ERA this past season, because he was dropped from a poor Giants rotation to make room for the illustrious Conner Menez just four months ago, well, we get that.

He doesn't exactly have the name value of Josh Hader or Craig Kimbrel. He doesn't have a consistent track record of success -- quite the opposite, as we'll show in a second. But because of what he did in the second half of the season, when he shifted to relief and was absolutely dominant, you have to change your opinion from what he's been to what he might be.

Pomeranz, in 28 2/3 innings as a reliever with the Giants and Brewers this year, faced 106 batters. He struck out 50 of them. That's 15.7 strikeouts per nine, or, more appropriately, a 47.2% strikeout rate. Those are wild numbers, so we're going to need to put them in context, and explain how in the world a just-OK starter managed to pull that off.

Let's get to it -- right after we enjoy a nasty Pomeranz curveball for a game-ending strikeout:

First, a quick recap of Pomeranz's up-and-down career. There's a lot happening here:

2010: Fifth overall pick in the Draft. Two of the four picks ahead of him were Bryce Harper and Manny Machado. One year after being drafted, he was traded to Colorado in the Ubaldo Jimenez deal.

2011-15: OK-ish young pitcher trying to make it work for Rockies & A's (4.07 ERA in 291 2/3 innings).

2016: Shockingly an All-Star starter for the Padres (2.47 ERA in 102 innings), followed by 68 2/3 innings of 4.59 ERA ball for the Red Sox following a trade.

2017: A very good season as a Red Sox starter (3.32 ERA in 173 2/3 innings).

2018: A very bad and injury-plagued season as a Red Sox swingman (6.08 ERA).

2019: A very bad half-season as a Giants starter (6.10 ERA in 72 1/3 innings) followed by a bullpen demotion and trade to Milwaukee ... and then pitching like the best reliever in the game (1.88 ERA and 50 strikeouts in 106 batters faced as a reliever.)

From 2011-18, Pomeranz had a 3.92 ERA and a 110 ERA+, making him slightly above average. If we look at FanGraphs' Wins Above Replacement, his 8.9 is tied for 121st most in that span, near names like Edwin Jackson and Bud Norris. He was mostly "fine," just with a lot of ups and downs on the way to being "fine."

It's too simplistic to compare every high Draft pick lefty starter who bounced around before becoming a dominant reliever to Andrew Miller, but ... there are some echoes here of Miller, aren't there? Miller was the sixth overall pick in 2006, spent parts of six seasons trying and mostly failing to be a starter for the Tigers, Marlins and Red Sox, eventually turning into one of the best relievers in baseball.

Enjoy Kyle Tucker swinging through a Pomeranz fastball, and then let's explain the numbers.

OK, so about that 47.2% strikeout rate: It's really, really good. Dating back to 2002, when these splits are easily accessible, we've had 4,585 seasons where a pitcher faced at least 100 batters as a reliever, and Pomeranz's strikeout rate is ... the sixth best.

Highest strikeout rate in a season, 2002-2019
(Min. 100 batters faced as a reliever)
52.5% -- Aroldis Chapman (CIN), 2014
50.2% -- Craig Kimbrel (ATL), 2012
49.6% -- Craig Kimbrel (BOS), 2017
49.1% -- Carter Capps (MIA), 2015
47.8% -- Josh Hader (MIL), 2019
47.2% -- Drew Pomeranz (SF/MIL), 2019

Other names in the top 10 include Eric Gagne's 2003, Miller's 2016 and Edwin Díaz's 2018, so this is basically a list of the most dominant relievers of the 21st century. (Aside from Capps, that is, who saw his career crumble amidst Tommy John surgery and controversy over the legality of his pitching delivery.)

So right away that's impressive, but the other pitchers on this list generally did this over an entire season. As impressive as the end of Pomeranz's 2019 was, it was only over a few weeks. That's not really fair to compare. So instead, let's get back to that "50 strikeouts in 106 batters" idea to try to put this on the same scale. In the 21st century, how many other relievers managed to whiff at least that many batters in a span of 106 hitters? How good were they overall, or into the future?

The answer, as it turns out, is quite a few. Thirty relievers have done this since 2000, including Pomeranz. A few of them -- think Chapman, Kimbrel and Kenley Jansen -- have done it on multiple occasions. (There's a lot of strikeouts these days.)

Let's loosely and somewhat subjectively break the other 29 into four groups, to see what this might mean for Pomeranz's future as a reliever. (For pitchers who did it more than once, only the most recent season will be shown. Some did it across multiple seasons.)

The studs

Josh Hader (2019), Edwin Díaz (2018), Craig Kimbrel (2017), Kenley Jansen (2017), Andrew Miller (2016), Dellin Betances (2016), Aroldis Chapman (2015), David Robertson (2014), Sean Doolittle (2014), Wade Davis (2014), Brad Lidge (2005), Eric Gagne (2003)

These guys have had multiple star-level seasons, and some might end up in the Hall of Fame. These are the cream of the crop.

The solid relievers

Adam Ottavino (2018), Chad Green (2017), Chris Devenski (2017), Corey Knebel (2017), Ken Giles (2016), Brad Boxberger (2014), Jason Grilli (2013), Rafael Betancourt (2011), Carlos Marmol (2010), Brian Fuentes (2008), Byung-Hyun Kim (2000)

A step down from the first list, these relievers weren't quite as good or as consistent, but they still were (or are) pitchers with at least a few productive seasons out of the bullpen.

The flukes

Carter Capps (2015)

Still only 29 years old, Capps didn't throw a Major League pitch in either of the last two seasons and is currently out of baseball.

The too-soon-to-says

Pomeranz, Héctor Neris, Nick Anderson, Kirby Yates, José Alvarado, Liam Hendriks (all 2019)

This group all did it for the first time in 2019, so their future is unwritten. Hendriks and Yates were probably the two best relievers in the game this past season. The relatively anonymous Anderson had a huge breakout season.

OK, so ... that's pretty good? Other than Capps, anyone who's done this over the last two decades has had some level of sustained success out of the bullpen. That's as you'd expect, because we're starting from the high bar of "having struck out at least 50 in a stretch of 106 batters." You don't get there by accident.

Neither, as it turns out, did Pomeranz. Here's how, and we'll take you to that with ... another beautiful-looking strikeout.

When a starter moves to the bullpen and finds success, there's generally two immediate things you think of: First, that without the need to pace himself, he can add velocity, and second, without the need to turn a lineup over several times, he can ditch his lesser pitches and focus on his best ones.

That's not the only way to do it, but it's the most common way. Pomeranz is no different.

“It’s always a challenge to figure out which guys are going to benefit from the bullpen," Brewers manager Craig Counsell told MLB.com in September. "Some guys, it’s the same. And then you see a guy like Drew, and it’s night and day. I think from Drew’s perspective, it’s, ‘I can just let it fly.’ That’s what he’s doing.”

No kidding. For years, Pomeranz's fastball velocity had hovered in the 91-93 mph range. In 2018, when he was struggling to stay healthy, he dipped below 90. As a starter in 2019, he was back up to 92 mph. As a reliever, he was up to 94.5 mph. On Sept. 7 against the Cubs, he throw a fastball a career-high 97.5 mph, which is apparently a thing he can do now.

The second part of the transformation is usually to "throw your good pitches and not your bad ones," which is a little oversimplified, except when it's exactly the thing that happens. (For example: Miller ditched his changeup and sinker when moving into relief, relying on his fastball and slider exclusively.) As a starter, Pomeranz regularly threw five pitches, adding a curve, a cutter and a changeup to four-seam and two-seam fastballs.

The problem was that the changeup was regularly crushed (career OPS: .942) and so was the sinker (career OPS: .922), while all of the non-curveball pitches just sort of blended into one fastball-esque mush. As 2019 went on, the four-seamer grew massively in importance, and the changeup, sinker and cutter all but disappeared.

As a starter in 2019, Pomeranz threw the two good pitches, the four-seamer and the curveball, 80% of the time. As a reliever, he threw them 95% of the time. That's not something you can do as a starter.

But this only works if you have a good pitch or two, and Pomeranz does. Way back in Spring Training of 2016, leading into that great first half with the Padres, we asked him about them, that high-spin fastball and the curve with great break.

"I've always had a pretty good fastball and it kind of gets on them, surprises them a bit," Pomeranz said at the time. "I've just always had the kind of fastball that jumps, in my mind."

Very much so. Due to 84th-percentile fastball spin, Pomeranz gets an extra 2.5 inches of rise on his four-seam compared to other fastballs at his velocity, and that, among those who threw 500, is elite. It's tied for 10th-best of 190 pitchers; among the names ahead of him: Chapman, Doolittle, Anderson and Hendriks, along with Gerrit Cole and Justin Verlander. Quite the coincidence, that.

You can see that clearly here, where Melky Cabrera swings under the ball, which hasn't dropped as much as he thought it would have.

Then there's the curveball, which doesn't actually have strong spin, but because of the angle in which he releases it, has excellent drop. There were 115 pitchers to throw at least 250 curveballs, and the 5.1 inches of extra vertical drop he gets on it is tied for 17th, behind more famous curves like those of Trevor Bauer, Seth Lugo, Walker Buehler and Cole.

If you combine the two lists, the only pitcher who has as much fastball rise and as much curveball drop as Pomeranz is Cole. We're certainly not saying Pomeranz is comparable to Cole, because he's not; Cole is more durable, throws harder and has several good pitches, not just two.

This, however, is often how relief aces are born. They try to start, and they can't stay healthy or consistent, or they realize they simply don't have enough good pitches to continue to fool hitters. What Pomeranz did to end 2019 might have been a small sample, but based on those who have done it before, it's not a fluke. Just look at the other names who have done it.

As we wrote back in 2016: "Pomeranz's strategy in disrupting the hitter's eye level is clear: curveballs down, fastballs high." It was true then, and it's true now. The difference is that moving to relief has made the fastball better, with more velocity, and it's allowed him to dump the lesser pitches to focus on the good ones.

That's why, despite the inconsistent track record, despite the 4.85 ERA this year, Pomeranz is going to be one of the most sought-after relievers this winter. It's not about his career record. It's about what you think he can do over the next few seasons.