The Detroit Tigers bullpen went the entire month of April without losing a game.
I'll let that sink in for a moment.
Props to Francisco Rodriguez for giving his best effort to ruin that streak a few times, but he wasn't successful. The revamped back end of Rodriguez, Mark Lowe, and Justin Wilson has drawn praise from fans for keeping their blood pressure down compared to previous years.
More than anything, the Tigers' bullpen has timed their increase in effectiveness well. The starting rotation is getting fewer outs than ever, averaging 5.4 innings per start, third-lowest in the American League. Having relievers that can do good things and not make us fans pull out our hair is pretty nice.
The bullpen ranks fourth in Major League Baseball in ERA, third in FIP, and are tied for fifth in fWAR. Context-dependent methods like the Tigers, as well. The bullpen's 1.32 WPA is 10th in baseball, and they are seventh with an RE24 of 11.72. Perhaps most refreshing of all, the bullpen has just four meltdowns on the year, the lowest total in baseball. All in all, the data seems to support a team that is solidly above average.
A funny thing is happening, though. The Tigers are collectively getting fewer strikeouts from their bullpen than ever before.
It's usually not a good sign to be worse than the replacement-level bullpens of 2014 and 2015 in a major statistical category. Outside of Justin Wilson, the bullpen doesn't have a true strikeout artist within it. Rodriguez, Lowe, Drew VerHagen, and Kyle Ryan all struggle to punch hitters out. In the era of Wade Davis and Kansas City's lockdown bullpen, that usually spells trouble for a relief corps.
The Tigers may have found a different path to success, though. Rather than trying to overpower hitters, the bullpen has shown an increased emphasis on lowering walk and home run rates while increasing ground ball rates. Check out how the first month of the season has compared to years past.
The walks are probably the most exciting part of this. As Jim Price is fond of saying (and Ian Krol will testify), walks will kill a reliever. Alex Wilson and Kyle Ryan are the embodiment of this new mentality, with one walk apiece in 21 2/3 combined innings. Justin Wilson and Mark Lowe have only allowed two each. This emphasis on curtailing walks is forcing opposing hitters to beat them by putting the ball in play.
In fact, the bullpen is forcing hitters to beat them on multiple balls in play. VerHagen and Lowe come in with reputations as ground ball specialists, and they have lived up to that billing so far. Both pitchers have posted ground ball rates near 60 percent with below average line drive rates. As a team, the Tigers' bullpen has the fourth-highest ground ball rate in the majors. Hitters are getting on top of the ball a lot against them, and aren't hitting for a lot of power. They may not necessarily be able to post low BABIPs as pitchers, but the Tigers' relievers are forcing two or even three hitters to reach in an inning to score.
Perhaps the Tigers haven't constructed the bullpen in the same method that other teams have. However, by ranking among the best in the league at walk and home run prevention, they have found a new level of success in locking games down.