Doug Mirabelli and Tim Wakefield
Baseball Player Won-Loss Records
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Controlling for Abilities of Teammates: example, Doug Mirabelli

In 2000, Doug Mirabelli committed 5 passed balls in 80 games for the San Francisco Giants, good for a (teammate-unadjusted) context-neutral Component 2 winning percentage of 0.592.

In 2003, Doug Mirabelli committed 14 passed balls in only 55 games for the Boston Red Sox, posting a (teammate-unadjusted) context-neutral Component 2 winning percentage of 0.481.

Did Doug Mirabelli really get that much worse in just three years? Well, he did age from 29 in 2000 to 32 in 2003, so some of that could be age-related decline. But, more significantly for Mirabelli, in 2003, he was the personal catcher for knuckleballer Tim Wakefield, who had a career (context-neutral, teammate-adjusted) Component 2 winning percentage of 0.255.

In order to make Player Won-Lost records meaningful as measures of player talent, it is necessary to control for the ability of one’s teammates. This is done using the Matchup Formula as described here.

The case of Doug Mirabelli, sometime personal catcher for knuckleballer Tim Wakefield, is instructive in this regard.

Doug Mirabelli’s teammate-unadjusted context-neutral Component 2 won-lost records over his career are as follows:

Year Team Wins Losses Win Pct
1996SFN0.020.040.329
1997SFN0.000.001.000
1998SFN0.010.010.564
1999SFN0.070.010.870
2000SFN0.180.120.592
2001TEX0.060.060.497
2001BOS0.130.170.436
2002BOS0.110.110.492
2003BOS0.100.110.481
2004BOS0.100.180.359
2005BOS0.060.070.481
2006SDN0.020.020.562
2006BOS0.130.200.387
2007BOS0.080.120.412
CAREER1.071.210.470


Outside of Boston over these years, Mirabelli’s Component 2 winning percentage was over 0.500 in five of seven seasons, with an overall winning percentage of 0.586. In contrast, Mirabelli’s Component 2 winning percentage was below 0.500 in six of his seven seasons in Boston, with an overall Component 2 winning percentage in Boston of 0.426. Overall, Mirabelli rates as a fairly poor catcher at preventing wild pitches and passed balls, with an overall Component 2 winning percentage of 0.470.

When Mirabelli’s Component 2 won-lost record is adjusted to control for the pitchers who Mirabelli caught, however, the results are the following:

Year Team Wins Losses Win Pct
1996SFN0.020.040.319
1997SFN0.00-0.001.014
1998SFN0.020.010.568
1999SFN0.070.010.852
2000SFN0.180.130.585
2001TEX0.060.060.492
2001BOS0.140.160.469
2002BOS0.110.100.530
2003BOS0.110.100.525
2004BOS0.130.160.457
2005BOS0.080.050.609
2006SDN0.020.020.532
2006BOS0.150.180.451
2007BOS0.100.100.503
CAREER1.181.110.516


Adjusting for the pitchers he caught, Doug Mirabelli turns out to have been slightly above average at preventing wild pitches and passed balls through his career. Outside of Boston over these years, Mirabelli’s Component 2 winning percentage remains fairly consistent after adjusting for his teammates, at 0.576. With Boston, on the other hand, Mirabelli’s combined Component 2 winning percentage improves dramatically from 0.426 unadjusted to 0.493 adjusted.

In words, adjusting for Mirabelli’s teammates brings his Component 2 winning percentages closer together over time. Mathematically, the standard deviation of Mirabelli’s winning percentages falls from 0.110 unadjusted – i.e., Mirabelli’s Component 2 winning percentages fell mostly in a range of 0.470 +/- 0.110 (0.360 - 0.581) – to 0.090 adjusted – i.e., Mirabelli’s Component 2 winning percentages range from 0.426 to 0.607 (0.516 +/- 0.090).

Mirabelli was still a bit worse in Boston than elsewhere. Of course, outside of one month in 2006 in San Diego, his career outside of Boston came at ages 25 – 30, while his Boston career was from ages 30 – 36. So based on age alone, we would have expected him to probably be a little less agile at blocking would-be wild pitches in Boston than in San Francisco and Texas.

It seems clear to me that the latter set of numbers more accurately reflect Doug Mirabelli’s ability to prevent wild pitches and passed balls.

All articles are written so that they pull data directly from the most recent version of the Player won-lost database. Hence, any numbers cited within these articles should automatically incorporate the most recent update to Player won-lost records. In some cases, however, the accompanying text may have been written based on previous versions of Player won-lost records. I apologize if this results in non-sensical text in any cases.

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