Baseball Prospectus defines defensive efficiency as follows:
I won't pretend to understand the math, but a higher number is good. Here's a little table about Tiger defensive efficiency, going back to the beginning of the Lost Years:
In the last years of Tiger Stadium, the Tigers were a bad defensive team, if inconsistently so. The 1997 team was actually excellent at generating a few extra outs while out on the diamond; it was the first year at short for Deivi Cruz, once a wizard with the glove, and the last at third for Travis Fryman, himself a former shortstop. The team's been consistently horrible since its move to the spacious confines of Comerica Park, or at least until this year. In 2005, the Tigers are once again near the top of the major leagues in defensive efficiency. Now, defensive stats are notoriously inaccurate and potentially fluky, but they're not entirely meaningless. BP doesn't publish individual defensive stats for the current year, but another kind is available: Bill James' Win Shares, from The Hardball Times. Win Shares are explained in some detail here and intense detail here, if you're not familiar with them. In short, they tell you how much a player, or in this case a player's defense, contributes to team wins, normalized for a bunch of factors and guided by Bill James' superb baseball intuition. You accumulate Win Shares both by playing well and playing a lot.
The fine gentlemen at THT, who count Tiger blogger Brian Borawski among their number, have been so kind as to provide in-season individual Win Share totals, with which we can begin to see which Tiger players are responsible for Detroit's stark defensive turnaround this year.
- At catcher, Ivan Rodriguez's 5.2 Fielding Win Shares (FWS) are second only to the Nats' Brian Schneider. Vance Wilson, despite a horrific first half at the plate, is also above average for a backup catcher, making the Tigers' backstops the third best defensive combination in the majors. Pudge had only 4.2 FWS all of last season. The reason is simple: only two errors so far in 2005.
- James considers the up-the-middle positions to be more important defensively, so first basemen, even Gold Glovers, simply can't rack up as many FWS as catchers or shortstops. Tiger first basemen have been adequate in 2005, though, with Carlos Pena nearly on pace to match his 2004 before an injury, Dmitri Young already there, and Chris Shelton at least not hurting himself or anyone else out there.
- At second, an improvement. Omar Infante is on pace to slightly surpass last season's reasonable total, but Placido Polanco has been gangbusters in FWS since joining the team a month ago. For Polanco, it's nothing new. He was the fourth-best 2B in the National League last year by FWS (though Jeff Kent led the league, a glaring hole in this here methodology). Polanco can also play a stellar third, something else for Dave Dombrowski to consider as July 31 approaches.
- At third base, keeping Inge on the field full time has made a massive difference. He is tied for the 2005 ML lead in FWS at third base, equaling last year's total across all positions in about 80% of the defensive innings. Simply getting Eric Munson (a third as good as Inge in 2004, before Inge's improvement) off the hot corner has been good for about half a win this year.
- Carlos Guillen was slightly below average at SS according to FWS both last year and this. He's not there to be Omar Vizquel, though.
- In the outfield, Craig Monroe is still playing a reasonable outfield and Rondell White is still staggering out there. Nook Logan, though, has been twice as effective as Alex Sanchez in center. As with replacing Eric Munson, getting Sanchez out of center field has been worth half a win.
Perhaps the improved defense at catcher, second, third, and in center field this year has helped players like Chris Spurling, Franklyn German, Kyle Farnsworth, and Nate Robertson post ERAs better than their peripheral numbers might indicate. Or perhaps these numbers are sample-size flukes. But Logan is fast out there, Pudge is consistent, Inge is on the field everyday, and the Tigers aren't giving up runs.