The Yankees Bullpen Has Been Unhittable —And Aaron Boone is Utilizing it Properly

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I took a look on Friday at the state of the Yankees offense a third of the way through the season. With a name like the Bronx Bombers, you might expect that the offense has been the star of the show—but the reality is that the pitching staff is powering the team’s success in 2019. The Yankee pitching staff has been perpetually underrated since 2017, ranking toward the top of the league in effectiveness during their recent run.

As good as the starters have been (more on that in a few days), it’s the bullpen that’s been the real star of the show in 2019, to nobody’s surprise. The Yanks have fully bought into the modern-day bullpen philosophy and the front office has clearly prioritized having a formidable bullpen corps as they’ve constructed their teams over the past few years.

And for good reason, as it’s worked: both the 2017 and 2018 iterations of the Yankee bullpen have set single-season fWAR records with 9.4 and 9.7, respectively. (The 2018 team also set a record for K/9, with over 11.) When the Yankees take the lead, they almost always hold it over the past two years. That’s a real luxury that fans should appreciate—seriously, I know we all mainly only watch NYY, but check out some other bullpens around the league try to hold down a lead. We’re spoiled.

And, after the Ottavino signing, this year’s corps was projected to be even better. Here is a sample of some headlines coming into the season:

  • Behind the building of a monstrous Yankees bullpen that can top itself (New York Post)
  • Yankees Reassemble Nightmarish Towering Bullpen of Doom (FanGraphs)
  • This Yankees ‘pen might be best ever … by far (
  • Have the Yankees assembled the best bullpen in baseball history? (Pinstripe Alley)
  • The Yankees are loading up in their bullpen, and it’s changing how they spend elsewhere (CBS Sports)

Expectations were sky high. Just over a third of the way through the season is enough of an Arbitrary Endpoint™ for me to take a look at how the vaunted bullpen is stacking up to expectations.

Overall Production

At the end of April, the great James Wagner of the New York Times wrote a piece on the Yanks’ bullpen performance through that point, finding that the team ranked 16th in bullpen ERA (4.45) and pointing out the unexpected struggles of Chad Green and Jonathan Holder.

Just about a month later, it’s fair to say that things have changed. (Just for the heck of it, NYY relievers have pitched to a 2.80 ERA in 128.2 IP since James’ article. They’ve accumulated a ridiculous 2.9 fWAR in that period.)

To the numbers, with team rankings in parentheses, as usual:

  • ERA: 3.63 (4th)
  • FIP: 3.55 (2nd)
  • K/9: 10.36 (2nd)
  • K%: 27.3% (3rd)
  • BB%: 9.7% (11th)
  • WHIP: 1.24 (5th)
  • Hard Contact%: 32.3% (2nd lowest)
  • Soft Contact%: 21.8% (1st, i.e. the Yanks induce the softest contact)
  • fWAR: 4.1 (1st, next closest: Tampa Bay and Cincinnati with 2.6)

That will do! The bullpen, even missing Dellin Betances and with Chad Green’s horrendous start, has been nearly unhittable. Some of these figures, particularly ERA and WHIP, vary wildly after each night and should be taken with a grain of salt. The others, though, are fairly representative: the Yanks miss tons of bats, and the contact they do allow is the softest in the league. That’s what matters most for future projections. They bats, induce soft contact, and limit the hard hit stuff. That’s a good formula right there.

In fact, opponents are hitting only .220/.302/.353 (.655 OPS) against the Yankee bullpen, meaning that opposing hitters turn into Baltimore’s Rio Ruiz when Boone makes the call to the pen. Again, that will do.

Adam Ottavino (the guy is outrageous), Zack Britton (his 75% ground ball rate is reminiscent of Baltimore Britton), and Aroldis Chapman (remember those early-season v-lo watches?) have been unhittable at the back end, powering most of this success. Innings 7, 8 and 9 are about as lock-down as you could ever hope for. But the fact of the matter is that there are few, if any, weak links in the pen—even everyone’s favorite punching bag in Cessa is fine for his role.

It’s also worth noting here that Dellin Betances, perhaps the best reliever of the bunch, has not thrown a single pitch in 2019. As with the offense, there are reasons to believe that the ‘pen is going to get even better and provide manager Aaron Boone with even more options.

Bullpen Usage and Leverage

To that end, much of the bullpen’s effectiveness depends on smart usage by the manager. Not coincidentally, that’s also where managers are subject to the most criticism by their fanbase. Boone is absolutely no exception there. (Including from yours truly. Honestly, Boone could lead the Yanks to 10 consecutive World Series and I still think I’d have a hard time forgiving him for Lance Lynn. I’m kidding, but only kind of.)

But criticizing for criticism’s sake is no way to operate, so it pays to, you know, do some research. So how has Boone done at managing the pen? Let’s first take a look at the Leverage Index, a tool which quantifies the importance of each appearance (with 1.0 being average), limited to the 6 guys who have been in the bullpen since Opening Day:

  • Adam Ottavino: 1.65
  • Aroldis Chapman: 1.53
  • Zack Britton: 1.37
  • Jonathan Holder: 1.32
  • Tommy Kahnle: 1.20
  • Luis Cessa: 1.03

That’s basically… ideal? Ottavino is clearly the best reliever in the pen right, so he should pitch in the highest-leverage situations. In fact, Saturday’s game was a perfect illustration of his usage: with two outs in the 7th and J.D. Martinez batting with a guy on in a one-run game, Boone turned to Ottavino. As Mike Axisa pointed out in his (always tremendous, well-worth it) Patreon column last week, Boone is using Ottavino like a true fireman.

Illustrating this point is the fact that the opposing OPS for batters Ottavino’s faced this year is .769, by far the highest in the NYY bullpen. Add this all up, and what you find is that the team’s best reliever is consistently facing the other team’s best hitters in the highest-leverage spots. Just how you’d draw it up. It’s great. (What’s not as great is the fact that next highest on the team is Luis Cessa at .760. Truth be told, though, that’s a function of the fact that someone has to pitch when the team is losing, even against good hitters. Cessa’s leverage index demonstrates this is exactly what is happening.)

Point is, that is (almost) the ideal bullpen usage right there. While I’d have liked to see Kahnle and Holder flipped in terms of leverage, the fact of the matter is that Kahnle had to work his way back into high-leverage innings after his atrocious 2018. I’d guess that we’ll see this change over the next few weeks now that Unhittable 2017 Postseason Tommy Kahnle is back. It will change even more when Betances comes back, too.

This tells us that it’s time for dominant narrative about Boone’s “bad” utilization of the bullpen to be put to bed. I wish he could use Ottavino and Britton all of the time, too, but if the Yanks are going to make a serious run in October, they’ll need them to be fresh and rested. That means you have to limit when and how you use them. Sucks, but it’s life. Something tells me we’ll keep hearing about this, though. Facts have never stopped a good narrative.


Not a whole lot here to dislike, even if you’re a Boone skeptic. The Yankee bullpen has been dominant and getting better. It will likely only continue to get better with the return of Betances. It could even be regaining an old weapon in Chad Green, if you believe his recent performance.

Better yet, manager Aaron Boone has deployed his weapons in a strategic way. Boone is even using the team’s best reliever like a true fireman. That’s something analytically-oriented fans have wanted for a long, long time. I love(d) Joe Girardi, but he never did this.

Yankee fans should feel extremely confident about the bullpen going forward —and opposing teams should hope that they score early.


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  1. overseasyankeefan

    Boone has indeed deployed his bullpen in a strategic way, using Ottavino as a true fireman & basing on match-ups to use Britton and Kahnle. Not sure if Girardi never did that but he did have a set role for each reliever that he said players appreciated. Boone actually was more like Girardi last season but this season so far, he has clearly changed/improved on the bullpen usage. One side note: I was really puzzled (an understatement!) why Boone put up Lance Lynn there instead of Britton based on his post-game explanation at the time but this spring training, the real reason why Boone didn’t use Britton at that critical situation was revealed by Britton himself. In hindsight, it might have be a tipping point for Britton to choose Bronx knowing that he would not be a closer (though of course the money was good and the contract offered enough security for him should things not work out). That being said, the lopsided embarrassing playoff game will forever stick out in history. It is even unpleasant to rethink that game right now…

  2. Chip

    It’s hard to make bad choices with a bullpen this good – especially when the weakest link (Green) has been both buried in the minors and held as an Opener – thus removing him from any potential use late in a big spot.

    Good job by Boone, good job by Cashman, good job by the pitchers themselves.

    Now let’s hope that the starters can start giving the team some length so these guys are still effective in August and September and October.

    • lightSABR

      …and they’ve done it all without Betances. Can you imagine what it would be like to have the full set healthy in the playoffs?

    • Your a Looser Trader FotD

      “We need length.”


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