Should the Yankees be concerned about Zack Britton’s increasing walk rate?

The Yankees won their 16th in a row against the lowly Orioles on Wednesday afternoon, shockingly battling through a close game that required Aaron Boone to deploy his top-tier relievers in the back of the bullpen. Zack Britton, one of Boone’s elite bullpen arms, pitched a scoreless eighth to maintain a one-run lead.

Britton did the job and lowered his season ERA to 2.17, but there was also the continuation of a concerning trend. Britton issued a leadoff walk to noted former Yankee legend Jace Peterson, marking Britton’s fifth straight outing that he had given up a free pass (he broke that streak on Friday night against Cleveland). Over his last 5.2 innings, the lefty has allowed seven walks. To be fair, Britton has allowed just three runs over his last 23.1 innings and aside from a memorable hiccup in Minnesota, which paved the way for the most exciting game of the season so far, Britton has been great at holding a lead.

Still, Britton’s outings tend to have an added tension to them, and one can point to the walks as a reason for that. Over those past 23.1 innings, Britton has struck out 16 batters, but has walked 17. His downtick in strikeouts has been concerning, but his league-high groundball rate has helped make up for that. As for his walk rate, this current stretch appears to be the continuation of a trend over the past few years, and his BB/9 this year has reached a concerning 5.26.

Britton’s walk rate of 14.3 percent in 2019 is in the bottom three percent of the league, per Statcast. What’s behind this trajectory that has reached a head in 2019, where Britton is walking batters at a rate that is near the worst in the league? For starters, Britton’s trademark power sinker hasn’t been generating nearly as many swing and misses this season as his peak in 2015-16.

Britton has also upped his slider usage this season, throwing it 11.8 percent of the time this season compared to 6.4 percent in 2018. That usage rate is Britton’s highest since 2013, when he appeared in just eight games, and opposing batters don’t seem to be biting against that slider as much as in the past.

Again, overall, Britton has been very dependable for the Yankees this season, but his seemingly decreasing control could cause problems in high leverage spots in the postseason, when more dangerous lineups with more disciplined hitters step in against him. For example, in 3.2 innings against the Astros this season, ranging from outings from April to June, Britton walked seven batters. Britton’s grounder-heavy stuff always leaves the door open for a double play, which has bailed him out of walks many times already this season, but that story could unfold differently should the Yanks meet teams like the Astros in October.

Britton’s walk rate is concerning, but he has also shown that he’s capable of regaining consistent control, similar to Aroldis Chapman recently. Back in July, Britton went eight straight outings without issuing a walk, and he could always run into a stretch like that again heading into the postseason. The Yankees, and their fans, sure hope that’s the case, or else Britton’s outings could result in a number of blood pressure spikes across Yankees Universe, even if his outings result in a zero in the run column.