Coming into 2013, the Tigers were expecting big things of Andy Dirks. In the offseason, Detroit added Torii Hunter and a healthy Victor Martinez while they bid adieu to Brennan Boesch and Delmon Young. Dirks, coming off a season where he hit .322, was expected to be a solid, if unspectacular, component of a potent lineup. Yet, at the All-Star Break, Dirks has been far from solid, posting an average of .243 and a slugging percentage 143 points below his 2012 mark. Over the Break, might Dave Dombrowski and Jim Leyland decide to replace Dirks with either Matt Tuiasosopo, Avisail Garcia, or Nick Castellanos?
Tuiasosopo has certainly been a massive surprise this season, with an AVG/OBP/SLG of .329/.450/.634, albeit in one third of Dirks's plate appearances. Tuiasosopo's weighted runs created plus (wRC+, a stat where 100 is major league average production and 101 is 1% more production than the average major leaguer) sits at 196 compared to Dirks's 78. That means that Tuiasosopo has provided two and a half times more production per plate appearance than Dirks. To put this stat in perspective, Prince Fielder's wRC+ is 125 while Cabrera's is at a league-leading 204. Tuiasospo's success isn't due to only being used against lefties either; Tuiasosopo's wRC+ is actually slightly higher while facing righties.
Avisail Garcia has gotten an extended look in the big leagues already this season. Jim Leyland has been adamant that Garcia needs to see everyday at-bats in order to continue his development, so although no one wants Garcia sitting on the bench in Detroit, if he were the everyday left fielder, that wouldn't be a problem. The problem, however, is that Garcia simply wasn't that good in Detroit. He actually was slightly worse than Dirks, while receiving only 12 less at-bats than Tuiasosopo. After being sent back down to Toledo Garcia has clobbered the ball, so there is reason to be optomistic should Garcia be given the chance to play everyday.
The third candidate, of course, is top-prospect Nick Castellanos. Castellanos has had no trouble in his first year in Toledo, and the main remaining concern is his defense in left. Whenever the Tigers have needed an extra outfield bat they have called up Garcia, but maybe Dombrowski would choose differently if he were calling up someone to play everyday.
Let's pretend for a moment that the Tigers do in fact want to make a change in left field. Switching Tuiasosopo and Dirks would be simple, but putting Garcia or Castellanos on the major league roster would be decidedly less so. The Tigers would be faced with the decision of optioning Dirks to Toledo or designating Don Kelly for assignment. There are not enough at-bats for Garcia/Castellanos plus Tuiasosopo and Dirks, and Kelly has had the better year so far with a wRC+ of 106 compared to 78, but Dirks definitely belongs in the major leagues, at worst as a fourth outfielder.
There is, however, one scenario where the Tigers may feel the need to call up either Garcia or Castellanos. If Peralta gets suspended or Infante is on the disabled list for an extended period of time, Kelly or Tuiasosopo may be called upon to play the middle infield. Now, no one knows if either player is capable of playing the middle infield, but both of them have played it in the past. If Tuiasosopo or Kelly were needed in the infield, Garcia or Castellanos could play everyday in left while Dirks would have much less competition for playing time as the fourth outfielder.
Going into the second half, Andy Dirks is squarely on the hot seat. Leyland and Dombrowski may or may not decide to make a change, but chances are they will at least discuss the possibility this week. There are many subjective factors in play here, namely Dirks's defensive ability -- he's the fourth best defender in all of baseball according the Fangraphs's Fielding Runs Above Average. Should the Tigers decide a change is needed, they have three quality candidates, who, given the opportunity, can provide a significant upgrade.