Can the Yankees trust Zach Britton?

The Yankees made several additions at this year’s trade deadline, and their first one may have been their starriest. Almost a week before the deadline, the Yankees flipped a trio of pitching prospects for Zach Britton, the highest-profile reliever on the market. Britton wasn’t pitching great at the time, but he seemed to be rounding into the form that made him one of the game’s premier closers from 2014 to 2017.

Since coming to New York, however, Britton has struggled. He’s allowed six runs in 9.1 innings in pinstripes, striking out eight batters and walking six. His numbers on the year are underwhelming: a 4.32 ERA in 25 innings, with a 7.6 K/9 rate and 5.8 BB/9 rate.

The Britton the Yankees hoped they were getting has yet to arrive, and with each passing outing, it seems less and less likely that the elite version of Britton will ever again re-emerge. Something is off here.ri

That something appears to be control. That much seems to be obvious at least based off his egregious walk totals, but the problem goes deeper. We can look at the rate at which Britton is throwing strikes using Baseball Prospecuts’ called strike probability (or CSPROB). CSPROB differs from other calculations of zone rate in a few crucial ways. Instead of looking at the rate at which a pitcher hits the “rulebook” strike zone, it looks at the probability each pitch he throws has of being called a strike, based on the actual zone called by the game’s actual umpires.

There are 427 pitchers to have thrown at least 25 innings this year. Among them, Britton ranks 401st in CSPROB. Each pitch he throws has just a 42% chance of being called a strike. The average among the pitchers in the sample was over 47%.

Britton has been extremely averse to the zone this year, but that’s not the only thing contributing to all the free passes he’s handing out. He’s never been one to pound the strike zone, often relying on opposing hitters to chase in order to generate whiffs and strikeouts. It’s those chases that he’s lacking this year.

During Britton’s sensational 2016 campaign, in which he posted a 0.54 ERA and didn’t blow a save, opposing hitters swung at 37% of the pitches he threw out of the zone. That’s a huge number for a pitcher that often avoids the zone, and it helped him post a 17% swinging strike rate. This year, hitters have chased just 25% of the time, leading to just an 11% swinging strike rate. All those extra takes means fewer whiffs, more walks, and fewer strikeouts.

What’s caused this erosion of deception? Perhaps Britton’s signature pitch, his devastating sinker, just doesn’t have the zip it used to. Consider this chart, courtesy of Brooks Baseball, showing the horizontal movement of Britton’s sinker:

Britton’s sinker, which is used to fly in on the hands of lefties and dart away from righties, has lost a couple inches of horizontal movement when compared to his 2016 peak. It also has about a quarter of an inch less sink.

Couple that with a notable drop in velocity, and it seems plausible that Britton’s sinker just doesn’t deceive hitters the way it used to. The pitch doesn’t move as much, and hitters have a bit more time to react to it with his diminished velocity. It all adds up to a .332 wOBA allowed on fastballs in 2018, compared to a .187 wOBA in 2016.

If Britton can’t rediscover his control or deception, the Yankees’ bullpen might never have the relief weapon it thought it was getting. Britton has time before the postseason commences to try to find himself, to establish himself as a dependable setup option based on his once devastating sinker. That Britton is not here today, though. If Britton doesn’t show obvious signs of improvement over the coming weeks, it will be difficult to trust him when the chips are on the table.