When Sean Casey was resgined I indicated I didn’t like the deal, but never really elaborated. My issue is that as nice a guy as Sean Casey is, he just isn’t very good.
Offensively Casey is at best an average hitter. His OPS+ since 2002 looks like this (OPS+ indexes a players OPS against the league average. 100 means the player is average, values above 100 mean above average)
Year OPS+ 2002 78 2003 98 2004 142 2005 104 2006 87
Over the last 5 seasons Casey has had 1 good year, 2 average years, and 2 bad years. Even if Casey can regain his earlier form, that merely means he is an average offensive player at a position where considerable offense is expected.
So for the sake of argument let’s assume that Casey gets back to be a league average hitter. That puts him slightly below average at his position. But what about defense?
David Pinto just released his Probablistic Model of Range numbers for first basemen and Sean Casey ranked only above Jason Giambi in terms of defense. According to PMR, Sean Casey made 24 plays fewer than expected in 2006. That is beyond bad. Keep in mind that due to the playing time that Casey missed, he was only in the field for approximately 2/3 of the season. A full season at first would have resulted in 32 missed plays for Casey.
But what is the impact of missing that many plays? If we take a very conservative approach and assume that each ball Casey missed resulted in a single (keeping in mind that a good portion probably resulted in double if they were down the line) we can estimate that each missed play cost his teams (Pirates and Tigers). The run value of a single is .47 and the run value of an out is -.28. So the cost of missing a play that results in a single is .75 runs. So Sean Casey’s fielding cost his teams at a minimum 18 runs.
So back to our hypothetical for next season in which Sean Casey is an average offensive player at an above average offensive position, you have to subtract 18 runs (or actually 24 runs over the course of a full season). If Casey can replicate 2005 when he was average and played almost a full season, that would be good enough for 98 runs over 162 games (he had 83 runs created over 137 games). So Casey’s net contribution would be about 74 runs.
But if not Casey then who? How about one Christopher Bob Shelton? But I know, Shelton was awful after April Looking at his May through July numbers he only generated 31 runs created. If he continued to hit at that anemic rate for a full season he would produce 62 runs. And defensively? During his 4 monts of 2006 he was nearly 10 plays better than expected again using Pinto’s PMR. That means he would save about 12 runs defensively over the course of a season.
So even an offensively inept Shelton would produce 73 runs for the team while Sean Casey returning to his career norms would contribute 74 runs. For all intents and purposes this is a push. And here’s the kicker, Shelton costs 1/10th of what Casey will cost next year. So really-bad Shelton is still as good as back-to-normal Casey at a fraction of the cost.
Career stats came from Baseball Reference. I also leaned heavily on David Pinto’s work at Baseball Musings not only for the defensive stats, but for the Day by Day Database to break down Shelton’s stats. Lee’s expertise from Tiger Tales was also very helpful.
The very brief explanation of PMR is that it looks at the handedness or the batter & pitcher, the park, the type of balls that are hit, where they are hit, and how hard they are hit. It then looks at what happened to see how often the various types of balls are turned into outs. It then applies that model to the balls hit to a particular fielder to see first how many outs they would be expected to make given what the rest of the league did, and then how many plays that fielder actually made.
One final note about defensive stats for first basemen. The stats cited only measure fielders performance on balls put in play by the batter. It doesn’t take into account their ability to handle throws from infielders so that is still a judgement call. It’s my estimation that Casey doesn’t bring anything extraordinary to the table in this regard and Shelton is adequate as well. I call this a push.