The Yankees are extremely good, and buoying the team’s recent run of success is its dominant bullpen corps. They slam the door shut when the team has a lead and keep it open when the offense needs to make a comeback. The front office has prioritized the bullpen as it builds a roster, and I think it’s safe to say that the Yanks’ bullpen prowess has been the team’s biggest competitive advantage in recent years. I mean, check out the team’s bullpen statistics since the start of 2016 (though Sunday’s game), with their league ranking in parentheses, as usual:

ERA: 3.62 (3rd lowest)

3.62 (3rd lowest) FIP: 3.67 (2nd lowest)

3.67 (2nd lowest) Innings Pitched: 2148.1 (12th)

2148.1 (12th) Strikeout Rate: 28% (1st)

28% (1st) Walk Rate: 9.3% (15th)

9.3% (15th) Strikeout/Walk Ratio: 3.01 (4th)

3.01 (4th) HR/9: 1.08 (10th)

1.08 (10th) Avg. Fastball Velocity: 95.2 mph (1st)

95.2 mph (1st) Win Probability Added: 19.96 (3rd)

19.96 (3rd) fWAR: 31.4 (1st, next closest is Houston at 23.4)

Yeah, that’s a dominating pen right there, and the era selected even include the massive bullpen sale at 2016’s deadline. The Yanks know how to build a bullpen. That much is for sure. Anyway, any bullpen is only as good as its closer–consistently blow saves and it won’t matter, especially to a pen’s reputation–and the Yankees have one of the best in the game in Aroldis Chapman.

Chapman, who is having a tremendous season, gives the Yankees the luxury to forget about the 9th inning, allowing Aaron Boone to feel comfortable using other top arms like Adam Ottavino or Zach Britton in high-leverage situations earlier in the game. It often feels like Chapman’s effectiveness gets lost in the shuffle, so I though his performance was worth a diving into. Let’s take a deeper look at the Yankee closer’s performance, shall we?

2019 Success

Did you know that only 2 relievers have been better than Chapman so far in 2019? I sure as hell did not know that, but it’s true–at least it’s true according to FanGraph’s WAR total. Check out the top 5 among qualified (0.3 innings pitched per team game, as in three-tenths of an inning):

Kirby Yates, San Diego: 3.0 Liam Hendricks, Oakland: 2.7 Aroldis Chapman, New York: 1.9 Felipe Vazquez, Pittsburgh: 1.8 Nick Anderson, Miami/Tampa Bay: 1.7

Basically, Yates and Hendricks are in a league of their own this year, but Chapman has been the best among the rest. That checks out, as Chapman owns a 2.36 ERA (2.23 FIP) with a 34.8% strikeout rate (17th out of 165), a 0.36 HR/9 (4th lowest), a .190 batting average against (16th lowest), and 35 saves (tied for 1st with Yates) in 49.2 innings pitched. That does the damn job.

Now, it’s only fair to note that Chapman has struggled a bit with walks this year, walking an above-average 10.6% of all batters he faces. That’s more than league average (8.5%) but not out of line with his career production. Here is his career walk percentage in graph form, with league average included:

This tells us a few things, but notably that: 1) Chapman has almost always walked more batters than average, 2) that his walk rate has significantly improved year-over-year from last season to this, and 3) that he’s only posted a lower walk rate 4 times in his 10 year career (and only twice since 2013).

A lot of fans feel anxiety when Chapman enters the game. I think Chapman’s walk rate being so high is why. But it’s important to remember that this is…about it against Chapman. Check out how batters fare against him in various situations:

Overall: .194/.282/.267 (.247 wOBA), 34.8% K rate

.194/.282/.267 (.247 wOBA), 34.8% K rate Against Lefties: .167/.234/.238 (.210 wOBA), 42.7% K rate

.167/.234/.238 (.210 wOBA), 42.7% K rate Against Righties: .203/.296/.275 (.258 wOBA), 32.7% K rate

.203/.296/.275 (.258 wOBA), 32.7% K rate High-Leverage: .200/.292/.291 (.259 wOBA), 36.4% K rate

.200/.292/.291 (.259 wOBA), 36.4% K rate With RISP: .115/.197/.192 (.117 wOBA), 35.5% K rate

In other words, Chapman is damn near unhittable in almost every circumstance. Walks are about it. He also completely dominates left-handed batters (those are some preposterous numbers) and hasn’t allowed virtually any damage with runners in scoring position in 2019. That is very good. It’s funny, Adam Ottavino and Tommy Kahnle have understandably attracted a huge amount of attention for their seasons, but it does feel like Chapman is flying under-the-radar. He’s been unstoppable so far.

A Less-Effective Fastball

These results are actually a bit more interesting than they initially seem because Chapman’s fastball–the pitch that made him famous, obviously–isn’t the same pitch it used to be. It’s still a very good pitch, but it’s not what it once was. His average fastball velocity has been falling every year since 2016. Check it out:

It feels a bit silly to say “his fastball is declining” given that he is sitting at 98+ mph on the heater in 2019, but hey, this is a guy who averaged 100+ mph for 4 consecutive seasons (2014-2017). That’s what allowed Chapman to attack batters like this in 2015 and still produce a K rate over 40%:

He wasn’t even trying to locate it. That’s just a guy who knows he can overpower the vast, vast majority of hitters. In other words, Chapman’s fastball is still fast–seriously, 98 mph is fast–but a lot of other relievers can do that, too. It’s just not quite as unique as it used to be. That’s true even of his max velocity. Check it out:

Again, this is still absurdly fast. It really is. It’s just not the same as it used to be. The results back this up, too. Let’s start by looking at the whiff-per-swing rate on the pitch, which is my favorite metric to evaluate a pitcher’s tools:

That’s a decline! A very significant one, in fact, totaling about 50% from 2015-2019. That means batters are making more contact, which is a bad recipe. As it happens, more contact is resulting in more damage, as evidenced by the batting average and wOBA against the pitch:

2015: .194 (.258 wOBA)

.194 (.258 wOBA) 2016: .149 (.198 wOBA)

.149 (.198 wOBA) 2017: .190 (.257 wOBA)

.190 (.257 wOBA) 2018: .185 (.330 wOBA)

.185 (.330 wOBA) 2019: .241 (.304 wOBA)

This helps bring home the point: the pitch is still an asset, significantly better than most pitches, but it’s not nearly as dominating as it was a few years ago. In other words, it’s really encouraging that Chapman is still having success–it shows a versatility that many people, myself included, probably wouldn’t have predicted.

A New Approach

As I’m sure you know by now, Chapman is incorporating many more sliders into his repertoire recently. That much is obvious, and we hear commenters discussing it often on the broadcast. It’s still jarring to see it in this form, though. Check out the usage graph:

That’s a pretty clear trend right there. Chapman went from a guy who threw four-seamers 82% of the time in 2016 to only 58% of the time in 2019. That’s quite a transition, and it does speak to the fact that his trademark heat isn’t quite the same as it used to be. He’s had to make a real adjustment.

The good news is that his slider is a real tool at his disposal: it misses bats, generates soft contact, offers a new look, and likely keeps hitters off-balance. Aroldis Chapman “shouldn’t” be throwing a slider, you know? Anyway, check out the whiff-per-swing rate over time:

That there’s some decline in this isn’t abnormal considering how much he uses it, but honestly? I’m surprised there’s not more. He even posted a 60% whiff-per-swing rate last year in his previous career-high for usage. That is not what I expected. Moreover, the pitch has always been a good option for Chapman–just one he didn’t need to use. Check out the batting average and wOBA against it:

2015: .156 (.267 wOBA)

.156 (.267 wOBA) 2016: .212 (.256 wOBA)

.212 (.256 wOBA) 2017: .216 (.263 wOBA)

.216 (.263 wOBA) 2018: .109 (.165 wOBA)

.109 (.165 wOBA) 2019: .167 (.224 wOBA)

That is one tough pitch right there, even as it is used more. That’s even true considering the fact that Chapman has a tendency to leave the pitch over the heart of the plate and up in the zone. I mean, look at this:

That’s a lot of balls down and in on righties, of course, but it’s also a lot middle-middle, isn’t it? Goes to show you how batters aren’t really looking for the pitch, in my opinion. Hard to sit on a slider when a guy can still blow past 100, even when that slider comes in at 85 mph and moves 253%, or 5+ inches, more than the typical slider does. Last year, it moved 456% more than average, or a full 7 inches more.

Chapman’s fastball might not be the same, but he’s clearly complemented the pitch with a vicious slider that is helping him retain his status as one of the league’s most dominant relief options.

Outlook

Chapman will make a critical decision about his opt-out following this season, which Steven has already covered in detail. I’m not sure if he’ll do it–I would not want to test those free agency waters at age 31 myself. With that said, though, he’s clearly demonstrated that he is more than a one-pitch pitcher.

Chapman has supplemented his legendary fastball with a slider equally effective, and he remains one of the best relievers in baseball as a result. That’s not ever a guarantee with relievers, who are famously volatile. (In old Internet baseball speak, the term is “fungible.”) That Chapman made this adjustment is a point in his favor. It’s a lot easier to feel comfortable about Chapman’s long-term outlook knowing that he’s not just willing to make an adjustment, but that he already has.

Anyway, the offseason is the offseason. That’ll come when it comes. For right now, we be confident entering the final stages of the 2019 season knowing that Chapman is there to close the door for the Yankees. Odds are, whomever the Yankees face in the postseason won’t have an option nearly as dominant at the back end of their pen.