I bet you think the Yankee bullpen has been disappointing, don’t you? The unit was hyped as being the true strength of the team, even better than a perhaps historically powerful offense. Some notable failures stick out in our collective mind, like David Robertson giving up a Justin Smoak grand slam in the first weekend of the season, or Chad Green blowing the lead in Houston a couple of weeks ago. Slight vulnerabilities in the supposed invincibility of the relief corps have many people convinced it has underperformed.

It really hasn’t, though.

Of course the Yankee bullpen is better than most in baseball, though, right? It’s the most expensive, has by far the most pedigree and everyone in the group throws 99 with a wipeout slider. So comparing the bullpen to the rest of baseball isn’t that insightful. They were always going to be better than league average, the same way the bullpen has ALWAYS been among the league’s best. There’s far more value in comparing the Yankee ‘pen to itself, since New York perennially boasts a game-shortening relief corps.

Over the last five years, 2017’s group of relievers was the best Yankee fans have seen, even though they may have slightly overperformed their peripherals. Mostly due to a rash of walks, for what it’s worth. Those walks have come down in 2018:

Dellin Betances has halved his walk rate, Chad Green’s free passes have dropped off, and even Chasen Shreve has been able find the strike zone with more consistency. The flaw and chief source of frustration of the 2017 bullpen was how often they’d walk opposing batters, and so far this year’s iteration has been able to cut that down. There is one significantly concerning trait of this year’s bullpen though, and I’m curious if you can identify it. Here’s a hint; look at graph #3. Or, look here:

Now, the Yankee relievers don’t give up a lot of contact, as you can see with their 12.64 K/9. When one of them comes into a game, they’re going to strike out close to half the batters they face. The batters that don’t strike out, though, are hitting the ball harder than ever, and that really is concerning.

We only have batted ball data that goes back to 2002, but the 2018 Yankee bullpen gives up the hardest contact of any Yankee team in that timeframe. They are, by that measure, the worst Yankee bullpen on record. Aroldis Chapman has yet to surrender a home run this year, but outside of him, every single Yankee reliever is giving up more hard contact than their career marks.

Hard contact is always concerning for a pitcher, since it overwhelmingly leads to home runs and other extra-base-hits. For a starter, this is problematic, as you can see by looking at a pitcher like Marcus Stroman. He gives up the hardest contact in all of baseball, and those hard-hit balls just put too many men on base for a guy to pitch effectively. The hard contact becomes doubly troublesome for relievers, because of the higher leverage involved.

Relievers, especially the top end of bullpens, naturally face higher-stress, higher-importance moments in the game, in the late innings when the score is close. In 2018, starting pitchers in MLB have faced an average leverage index of 0.96, while relievers deal with an average pLI of 1.08. Combining higher leverage with harder contact surrendered - just like the Yankee bullpen is going through - can be disastrous, and has contributed to most of the “disappointment” fans have felt in the team’s relief performance.

So, what can be done about this hard contact problem?

The best proposal, in my opinion, is to double down on what has brought the Yankee ‘pen success in the first place. It’s no secret the Yankees throw fewer fastballs than anyone in baseball, but that truth extends to the flamethrowing bullpen as well. At just 51.4%, Yankee relievers rank 25th in baseball in FB%, despite the hardest fastball velocity. The Yankees can do this because of the power of the group’s offspeed offerings, which generate the fifth-most swings in baseball and the lowest level of contact out of the zone. Basically, the sliders, curves and changeups the bullpen throw end up outside the strike zone, but are whiffed on anyway. It’s almost impossible to hit an offspeed pitch hard if it’s out of the strike zone, and the Yankees should press that advantage.

Dellin Betances is just about the only reliever with a documented problem with his breaking ball, and indeed falling back on his fastball is at least partially responsible for his return to form this year. For the rest of the bullpen, though, the fastball has become the enemy. In short, all Yankee pitchers should be more like Aroldis Chapman:

A career high in slider usage has not only helped Chappy notch the second-best strikeout rate of his career - and with Chapman, that’s really saying something - it has led to him keeping the ball in the ballpark, and when contact IS made, hitters are popping up more than ever.

Chapman is eventually going to give up a home run or two, of course. But his approach is noticeably different this year, and it should serve as an object lesson to the entire bullpen. The Yankee relief corps is very good, but if they want to allay the very real fears around hard contact, the best way to start is reduce fastball usage.