Jon Morosi is speculating that the Tigers will decline Jhonny Peralta's $7.5 million option for 2011 and may instead sign him two a two-year deal for less money annually. He would, of course be the Tigers starting shortstop if he does sign. During his time with the Tigers, Peralta batted .253/.314/.396. There was much talk about his being rejuvenated by coming to Detroit. However, his Cleveland numbers were almost identical (.246/.308/.389).
Over the last three years, he has batted .260/.319/.414. His 0.3 Batting Runs (wRAA) tell us that he has contributed 0.3 runs above the average player with the same number of outs. In other wards, he has been about as average as you can get offensively. Since most shortstops hit below average, being an average hitter is a good thing. The three-year figure includes his stronger 2008 season. Over the last two years, he has -14.2 Batting Runs which is still pretty good for a shortstop.
The concern is his defense. Based on observation, he seems to make the routine plays, but lacks range. The Table below presents three popular defensive metrics - Defensive Runs Saved (DRS), Ultimate Zone Rating (UZR) and Total Zone (TZ) - for 2005-2010. All of the figures are runs saved above the average shortstop. The final column is the average of the three measures. The first four years are at shortstop only. The 2009-2010 numbers include both shortstop and third base as he didn't have enough innings at shortstop for his shortstop-only number to be useful.
Table 2: Jhonny Peralta - Runs Saved Above Average, 2005-2010
Peralta's defensive numbers have been below average for the most part, but not horribly below average except for 2006 where his average was -10. If we can believe a mix of numbers from two different positions, he actually looks about average the last two years. I'm more inclined to go with his earlier numbers which come from a lot of innings at the position he'll be playing.
So, I'll conclude that he's a little below average as a defender.
His combination of decent offense and below average defense make him an adequate option at shortstop. With another adequate option at third and a question mark at second base, it makes me nervous to hear about a possible two-year deal for Peralta. With more and more teams going with strong defense over offense at key up-the-middle positions, they may be putting their pitching staff at a disadvantage. This is especially true of Rick Porcello who thrives on strong infield defense. Kurt Mensching expresses similar concerns.
So, I'm thinking I'd rather not see them lock up Peralta for two years.