With the report the Tigers will be losing their All-Star shortstop Jhonny Peralta for 50 games, unable to return until the final three games of the 2013 regular season, any reasonable analysis shows that the loss of Peralta will be a major blow to the Tiger lineup.
Jhonny Peralta has been the most productive hitter from the shortstop position in major league baseball so far in the 2013 season, with a weighted on base percentage (wOBA) of .358. Among Ameircan League shortstops, JJ Hardy of the Baltimore Orioles is a distant second at just .311. wOBA is the most accurate measure of a player’s hitting contribution to his team. Translated from a percentage to a raw number, Peralta’s 128 runs created (RC) also leads the majors.
Using other metrics for good measure, Peralta also leads all shortstops in the league in On base percentage, slugging percentage, OPS, and WAR, and is second to only Hardy in home runs and RBI. In fact, Peralta leads all AL shortstops in WAR from 2011- 2013.
Among Tiger players, Peralta has been second only to Miguel Cabrera in terms of production at the plate. He ranks second in WAR, wOBA, batting average, and OBP, and third in slugging and OPS.
Peralta's rank among AL shortstops, 2013
|AL SS rank
Tigers’ General Manager, Dave Dombrowski, did well to mitigate the damage caused by Peralta’s suspension by acquiring slick fielding Jose Iglesias. Iglesias can fill in for Miguel Cabrera at third base, or for Omar Infante at second. However, Iglesias will not replace the overall production of Peralta, no matter how good his defense is at shortstop.
For one thing, Peralta has been an above average shortstop defensively, both in 2012 and in 2013 according to the advanced metrics available. In fact, Peralta led all shortstops in the American league in revised zone range (RZR) which is the percentage of balls hit to the shortstop’s zone that are turned into outs. The zone is the same for every player, and Peralta led them all. Between 2012 and 2013, to get a larger sample size, Peralta ranks second in RZR.
Using UZR, Peralta was second in the AL in 2012, and second between 2012 and 2013. Peralta has a dWAR of 0.8 for the 2013 season. If you like fielding percentage (which I don't), Peralta leads the league both this season and from 2012 to 2013. He is a very steady, if unspectacular shortstop.
Iglesias is a great defensive shortstop. That is a given, and we don’t need to go into any numbers to demonstrate that. We’ve seen time and again how small samples, and that’s all we have for the newest Tiger, are an unreliable measure of defensive performance in any case. But let’s say, for the sake of argument, that Iglesias is equal to the best shortstop in the league in 2012, and Peralta provides the same level of defense that he has been averaging, either in 2013, or over a two or three year period. Take your pick. Iglesias would save 2.3 runs defensively over Peralta over the course of a season. He would have to hit better than Prince Fielder has hit this year to equal Peralta’s overall production
These numbers demonstrate just how important Peralta has been to the Tigers this season. But let’s say his production is not sustained. Let’s say we assume that he will drop to 2012 levels at the plate, one of the worst seasons of his career. Well, Peralta was still above average for a shortstop, both offensively and defensively.
Iglesias has hit .257/ .307/ .314/ .622 in four seasons in the minor leagues. He hit less than that in three seasons at the Triple-A level. The entertainment value of watching a defensive whiz kid making plays that are well outside the shortstop’s zone may help to ease the loss of Peralta, but by no means can Iglesias replace what Peralta has been doing for the Tigers overall.
There should be no debate about whether the Tigers should use Peralta as their every day shortstop when his suspension is over. To do otherwise would be foolish.
Finding a shortstop who can field and hit well is no easy task. It is not fair to expect that Iglesias will do that. The complaints about Peralta’s defense have been largely unfounded, even though he doesn’t make a lot of plays outside the normal shortstop’s zone. As the Tigers found out when they had to replace Jose Valverde earlier this season, sometimes you just don’t know what you’ve got until it’s gone. Well, we’re about to find out.