Ivan Rodriguez is ruining his legacy.  Not because he is a below league-average hitter or a declining handler of pitchers, as Asher suggests.  On the contrary, it has more to do with the teams he is choosing to play for than it does his decline in playing ability.  Ivan Rodriguez has a well-justified reputation of being a winner who turns poor teams into playoff contenders, but since the 2007 season, that legacy is beginning to fade.

In The New Bill James Historical Baseball Abstract, James lists some of the highest position player winning percentages of all-time.  Meaning, he takes the winning percentage for each of the teams a player has played for, weighs them by the player's games played in a season, and calculates winning percentage for an individual player.  The highest one he lists is Yogi Berra at .621.  Of course, Yogi played most of his career with Mickey Mantle (.590) Whitey Ford (.690), and a host of All-Star caliber players.  Indeed, this sort of statistic is more of the "gee, isn't that interesting" variety than the "gee, isn't that revealing" variety, although that didn't dissuade James from using it as a major point in his argument that Eddie Collins was a better player than Rogers Hornsby was...

In a similar manner, Ivan Rodriguez has been well-known for bringing winning ways with him wherever he goes.  In 2003, he led a Florida Marlins squad that finished with a losing record the previous season to a World Series win.  In 2004, his arrival in Detroit corresponded with a win increase of 29 from their historically bad 2003 season.  By 2006, he had guided the franchise to its first winning season in 13 years and its only playoff appearance in 19 years.

Certainly, this is one missing component from James' analysis.  We need to know not only how good a team was with the player in question, but how that team fared before and after his time in that uniform in order to estimate his overall impact on winning.  So consider, in I-Rod's career from 1991-2007, how the Detroit Tigers, Florida Marlins, and Texas Rangers performed both with and without Rodriguez:

The Rangers have only finished with a winning record once since letting Rodriguez test the free agent waters, even though they did so five times with the squat catcher around.  The Marlins have only been able to surpass 83 wins once in their non-I-Rod history.  The Tigers never finished with fewer than 70 wins with Rodriguez, but they did so in eight out of the 10 years preceding his arrival.

Of course, this analysis has its imperfections as well.  the 1994 Tigers featured none of the same players as the 2004 Tigers did.  The newly-formed expansion Marlins looked a great deal different than the star-studded Fish of 2003.  The Rangers, who were third in total payroll in 2002, dipped to 21st by 2007.  We need to account for these variances; I-Rod might not have been able to save the 1993 Marlins, 1996 Tigers, or 2007 Rangers.  Those teams weren't anything like the ones that Rodriguez played for.

So what happens when we examine just the one-, two-, and three-year spans of I-Rod's absence that are nearest to his time with each club?  His contributions to the Marlins look a bit less impressive, however his value to the Tigers and Rangers appears even higher:

Of course, Mr. Rodriguez messed all of this up, didn't he?  The 2008 Tigers fell so far short of expectations that he was traded to the New York Yankees, who promptly failed to miss the playoffs for the first time in the Wild Card era.  The 2009 Astros are almost certainly going to become the third Houston Astros team to finish with a losing record since 1992.  Even if Ivan's current success at the plate holds up for a full season, his legacy of improving every team he graces with his presence is waning.

Or is it?  The one aspect of I-Rod's contribution to winning that we have not yet examined is on the single season level.  On each team for which Rodriguez has played, what was the team's record in contests in which he started versus contests that he did not?

Amazing!  12 of the last 13 teams Ivan Rodriguez has played for benefited from his presence.  Since 1998, whenever Pudge started a game, his teams have had a .530 winning percentage.  Whenever his backup has started, the team has won less than 45% of its games.  Pudge may have been a bit overrated early in his career due to his lack of offense, but he also may be underrated now despite his declining offense.

So if Ivan Rodriguez hangs around for another five years providing middling offense for unimpressive teams, don't let it fool you.  I-Rod deserves his reputation as a winning player, and the later stages of his career are more productive than they appear at a quick glance.