In the pitching world of 2021, every pitcher, it seems, is trying to make sure they can do at least one of these three things, if not all of them: A) throw a fastball with great velocity; B) throw that fastball with "rising" action; and C) not actually throw that fastball that often in favor of more and more breaking pitches with ever-increasing movement.

In Pittsburgh, one reliever is doing exactly none of those things ... and it's working.

Richard Rodríguez, 31 years old and a likely trade candidate at the July 30 Deadline, does not throw hard. His fastball does not rise. He has a slider, but he barely uses it, instead throwing almost exclusively fastballs, which, again, are of moderate velocity and below-average rise.

If modern baseball is endlessly a game of zigging while everyone else is zagging, then Rodríguez is … well, he’s off doing his own thing entirely, isn’t he? It’s working, too. Rodríguez has allowed just two runs this year, giving him an 0.86 ERA, and he's sandwiched between Corbin Burnes and Jacob deGrom in the Statcast expected ERA leaderboards. He’s walked a single hitter, and none in his past 19 games. Nine out of 10 pitches he throws are fastballs; last Thursday, when he closed out a Pittsburgh victory over Atlanta, he threw 27 pitches … all fastballs.

It's not just this year, either. Since the start of 2020, he's got a 1.83 ERA; he's got 50 strikeouts and only six walks.

How is that even possible? The answer might matter a lot to teams potentially interested in picking up another arm for a contending run.

Fastballs. So many fastballs.

Rodríguez threw four more fastballs while you were reading that, probably, and we really can’t overstate how many fastballs this man throws. Just look at this. This is all he does. Fastballs a bit high in the zone. Every now and then, a slider low, but mostly bounced in the dirt and non-competitive; he's induced just 12 swings against it all season.

Dating back to the dawn of the pitch-tracking era in 2008, there have been 4,603 different seasons when a pitcher has thrown at least 250 pitches. Only four of those seasons -- less than one-tenth of 1% -- have seen a pitcher throw 90% four-seamers.

Highest four-seam usage, 2008-21

96.4% -- Jake McGee, 2020
92.3% -- Jake McGee, 2017
90.8% -- Sean Doolittle, 2021
90.2% -- Richard Rodríguez, 2021
89.5% -- Tony Cingrani, 2016
88.4% -- Colin Poche, 2019

But notice something about that list, won’t you? McGee throws lefty. Doolittle’s a lefty. So is Cingrani, and Poche, and if you continue down the list you’ll see a few more seasons by McGee and Doolittle as well as lefties Aroldis Chapman, Matt Thornton and Kevin Siegrist. If you look at just righties, then not only is Rodríguez throwing more fastballs than any righty on record, he’s doing so by a lot.

So you might expect there to be something special about his fastball, like Chapman’s elite velocity. It’s not that; Rodríguez averages 93 mph, about league average. Maybe you’d think you’d get that outstanding rising action, like Doolittle or Poche. Not that either; Rodríguez gets 1.2 inches less rise than other fastballs at his velocity.

If it’s not that, what is it? It’s not velocity. It’s not vertical action. It’s horizontal, where, if you look at pitchers with 100 fastballs thrown, his four-seamer has some of the strongest cutting action in the game.

It's not a two-seamer or a cutter because he doesn't call it that, but it might be helpful to think of it that way. Whatever it is, he’s throwing it so often, in fact, and so effectively, that it’s been one of the most valuable pitches in the game this year.

But not, interestingly, for strikeouts. Or not exclusively so, anyway, which is fascinating because last year he posted an elite strikeout rate (16th best, among pitchers with 10 innings, at 37%), again mostly using the fastball. (Which, interestingly, showed up as a close comparison to Trevor Bauer's, in terms of spin, velocity and total movement, though Bauer's is more of a vertical riser, unlike Rodriguez's.)

This year, that's down to a more average 24%. What he's doing instead in 2021 is to generate the fourth-weakest contact of any regular pitcher. That is, his hard-hit rate is about league average; nothing special there. But he's avoiding that damage coming in areas where it might hurt him, because he's got the seventh-lowest line-drive rate and he's virtually in a tie for the highest fly-ball rate. Put another way -- among pitchers who have allowed 25 batted balls -- he has the third-highest rate of their batted balls becoming fly balls and/or popups. You'd expect some of those fly balls to land over the fence eventually, but popups, well, those are free outs. They're basically strikeouts.

Now: Is that a sustainable skill? Clearly there's something about the fastball that's working. In 2018, Rodríguez, in his first season with the Pirates, also threw a ton of fastballs, enough to have one of the 10 most valuable pitches that year, too, and it gained him some notice on the pages of FanGraphs that season, noting that even just over the first few weeks of the year, he'd contributed enough value to be quite the find given how the Pirates acquired him. But that was different. Rodríguez threw his slider a quarter of the time that year, and he was more of a strikeout artist that year (32%).

It's that change from whiffs to a very particular kind of contact that's made some of the ERA estimators wary, like expected FIP (4.68) or DRA (4.01), neither of which you think, probably correctly, you can induce this many fly balls without a few more flying over the fence. Not that anyone thought he'd stick to an 0.86 ERA all year long, anyway. It's for that reason that it's unlikely a contending team would likely trade for him in order to immediately make him their closer, as Pittsburgh is doing.

Then again, lots of teams need lots of relievers. Rodríguez isn't likely the best arm on a great team. But as a solid member of a bullpen core, you could do a lot worse. You couldn't possibly see more fastballs, though. It's all he does. It's somehow continuing to work.