When the Tigers lost starters Max Scherzer to free agency and Rick Porcello to trade, there was a lot of concern about the Tigers staff in 2015. Concern turned to angst when another starter Justin Verlander went down with a triceps strain in spring training. They would now have to rely on Shane Greene, Kyle Lobstein and Alfredo Simon to keep opposing offenses in check. That combined with a very questionable bullpen made the Tigers ability to prevent runs appear to be daunting task. But here we are almost a quarter of the way through the season and the the Tigers have allowed only 4.1 runs per game which is actually down from 4.3 last year. How is this happening?
As it turns out, Geene, Lobstein and Simon have held their own and the bullpen, led by new closer Yoakim Soria, has not been bad. However, right-handed starter Anibal Sanchez has struggled and Price has not quite replaced Scherzer's performance of the last two years. Various measures of pitcher contribution to run prevention show that the Tigers staff has not been as good this year. The standard FIP statistic has increased from 3.60 in 2014 to 3.76 in 2015. Other measures make the staff look even worse with xFIP ring from 3.76 to 4.11 and SIERA from 3.71 to 4.15.
So, while the staff has not been awful, it is not the reason for the improved run prevention. That leaves the defense and the gains there have been remarkable. The upgrades have been clear to anyone who follows the team closely. A now healthy Jose Iglesias has been a magician at shortstop and the outfield defense has improved markedly with the additions of left fielder Yoenis Cespedes and center fielder Anthony Gose and the subtraction of right fielder Torii Hunter. Even third baseman Nick Castellanos has gotten better at third base
Last year, defense cost the the Tigers 65 runs according to the Defensive Runs Saved (DRS) and I pointed out before the season that the Tigers could gain roughly six wins with only any average defense. Thus far, the Tigers have been even better than average with fielders saving them 15 runs by DRS. If they continue to save runs at the same place, they would be up to +60 by season's end which would be a 12 game improvement over last year! More conservatively, if they stay at +15, that would be an eight win improvement over last year. Either way that is a lot of wins for a defensive unit.
After years of watching fielders stumble and fumble around Comerica Park, the Tigers finally have a defensive team that is fun to watch. The improvement is obvious both to the eyes and to the calculator.
Data from the post were abstracted from FanGraphs.com.