Baseball Player Won-Loss Records
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Component 5: Hits vs. Outs on Balls in Play

In the fifth step of calculating Player Wins and Losses, batters, pitchers, and fielders are given credit and blame for balls in play becoming hits or outs.

1.    Calculation of Component 5 Player Game Points
Credits/debits for whether balls in play become hits or outs are assigned in Component 5. The average value of the ball in play, based on the location and hit type of the ball, was assigned to batters and pitchers in Component 4. Component 5 player wins and losses are calculated based on an average result of the play, given that it is either a hit or an out. For hits, debits and credits based on the type of hit – single, double, or triple – are assigned in Component 6. Credits for double plays, and baserunner outs and advancements are assigned in Components 7, 8, and 9, respectively. For fielders, Component 5 Player Game Points are the portion of Player won-lost records that are most comparable to other play-by-play measures of fielding, such as UZR, PMR, +/-, and TotalZone.

2.    Division of Component 5 Game Points Between Pitchers and Fielders
Component 5 Player Games are shared between pitchers and fielders based on the extent to which player winning percentages persist across different sample periods. The mathematics underlying this division is described elsewhere.

To summarize, one measure of the extent to which a particular factor is a skill is the extent to which a player’s winning percentage persists over time. To evaluate the persistence of skills, I fit a simple persistence equation which modeled Component 5 winning percentage on even-numbered plays as a function of Component 5 winning percentage on odd-numbered plays:

(Component 5 Win Pct)Even = b•(Component 5 Win Pct)Odd + (1-b)•(WinPct)Baseline

where (WinPct)Baseline represents a baseline winning percentage toward which Component 5 winning percentages regress over time.

Equations of this type were fit for Component 5 Player Game Points for pitchers and fielders. Separate equations were estimated for each fielding position (except for pitcher, obviously). The results for these equations are shown below. A brief explanation of these variables follows.

The number n is the number of players over whom the equation was estimated, that is, who accumulated any Player wins and/or losses on both odd- and even-numbered plays. The value R2 measures the percentage of variation in the dependent variable (WinPctEven) explained by the equation (i.e., explained by WinPctOdd). The numbers in parentheses are t-statistics. T-statistics measure the significance of b, that is, the confidence we have that b is greater than zero. The greater the t-statistic, the more confident we are that the true value of b is greater than zero. Roughly speaking, if the t-statistic is greater than 2, then we can be at least 95% certain that the true value of b is greater than zero (assuming that certain statistical assumptions regarding our model hold). The value of (WinPct)Baseline, the baseline winning percentage toward which winning percentages regress over time, is set equal to 0.500 by construction.
note: To be precise, I estimate unique Persistence Equations for every season, which use all of my data in all of these equations, but weight the data based on how close to the season of interest it is. The equations shown here weight each season equally.

Persistence of Component 5 Winning Percentage: Catcher
Pitchers:  n = 37,859, R2 = -0.0521
WinPctEven = (5.46%)•WinPctOdd + (94.54%)•0.5000 (10.81)
Catchers:  n = 8,047, R2 = -0.0000
WinPctEven = (10.87%)•WinPctOdd + (89.13%)•0.5000 (9.935)
The percentage of Component 5.2 Player decisions which are attributed to pitchers is set equal to the pitcher persistence coefficient (5.5%) divided by the sum of the persistence coefficients for pitchers and catchers (5.5% + 10.9%). This leads to 33.4% of Component 5.2 decisions being allocated to pitchers and 66.6% of Component 5.2 decisions allocated to catchers.

Persistence of Component 5 Winning Percentage: First Baseman
Pitchers:  n = 38,556, R2 = 0.0077
WinPctEven = (14.16%)•WinPctOdd + (85.84%)•0.5000 (27.61)
First Basemen:  n = 10,140, R2 = 0.0544
WinPctEven = (26.40%)•WinPctOdd + (73.60%)•0.5000 (25.98)
The breakdown of Component 5.3 Player decisions is 34.9% for pitchers versus 65.1% for first basemen.

Persistence of Component 5 Winning Percentage: Second Baseman
Pitchers:  n = 38,741, R2 = -0.0189
WinPctEven = (14.38%)•WinPctOdd + (85.62%)•0.5000 (28.16)
Second Basemen:  n = 9,500, R2 = 0.1006
WinPctEven = (34.44%)•WinPctOdd + (65.56%)•0.5000 (34.55)
Based on these results, Component 5.4 Player decisions are allocated 29.5% to pitchers and 70.5% to second basemen.

Persistence of Component 5 Winning Percentage: Third Baseman
Pitchers:  n = 38,670, R2 = -0.0200
WinPctEven = (13.37%)•WinPctOdd + (86.63%)•0.5000 (26.74)
Third Basemen:  n = 10,520, R2 = 0.1122
WinPctEven = (37.07%)•WinPctOdd + (62.93%)•0.5000 (40.54)
For Component 5.5, Player decisions are split 26.5% for pitchers, 73.5% for third basemen.

Persistence of Component 5 Winning Percentage: Shortstop
Pitchers:  n = 38,753, R2 = -0.0189
WinPctEven = (11.20%)•WinPctOdd + (88.80%)•0.5000 (22.26)
Shortstop:  n = 8,396, R2 = 0.0826
WinPctEven = (35.93%)•WinPctOdd + (64.07%)•0.5000 (33.48)
Pitchers receive 23.8% of the credit for Component 5.6 Player decisions, while shortstops earn 76.2%. Shortstops and third basemen earn a somewhat largest share of Component 5 decisions than first and second basemen. This makes a certain amount of sense to me. These positions are, perhaps, more difficult to field than first or second base, thereby allowing for a greater spread in the observed talent of fielders on this side of the infield.

Persistence of Component 5 Winning Percentage: Left Fielder
Pitchers:  n = 38,596, R2 = 0.0099
WinPctEven = (22.89%)•WinPctOdd + (77.11%)•0.5000 (46.05)
Left Fielders:  n = 14,522, R2 = 0.1447
WinPctEven = (40.17%)•WinPctOdd + (59.83%)•0.5000 (51.73)
Left fielders receive 0.0% of Component 5 Player decisions, while pitchers earn 100.0% of Component 5.7 decisions.

Persistence of Component 5 Winning Percentage: Center Fielder
Pitchers:  n = 38,674, R2 = -0.0002
WinPctEven = (18.03%)•WinPctOdd + (81.97%)•0.5000 (35.47)
Center Fielders:  n = 10,050, R2 = 0.1684
WinPctEven = (41.23%)•WinPctOdd + (58.77%)•0.5000 (48.05)
Based on these results, Component 5.8 Player decisions are allocated 30.4% to pitchers and 69.6% to center fielders. Center fielders therefore earn the highest percentage of Component 5 player decisions of the three outfield positions. As with shortstops and third basemen, the relative difficulty of fielding center field (as compared to left field or right field) allows for more observable separation in the fielding quality of center fielders, leading to higher and more significant persistence of center fielders' Component 5 winning percentage.

Persistence of Component 5 Winning Percentage: Right Fielder
Pitchers:  n = 38,558, R2 = 0.0071
WinPctEven = (22.35%)•WinPctOdd + (77.65%)•0.5000 (44.67)
Right Fielders:  n = 13,164, R2 = 0.1392
WinPctEven = (41.54%)•WinPctOdd + (58.46%)•0.5000 (49.87)
Component 5.9 Player decisions are allocated 35.0% to pitchers and 65.0% to right fielders.

Overall, pitchers earn about 33.1% of defensive Component 5 Player decisions, including 4.0% of Component 5 player decisions which are compiled on balls-in-play that are fielded by the pitcher. Excluding pitchers and catchers, infielders are allocated about 71.9% of Component 5 Player decisions involving them, while outfielders are allocated 65.1% of relevant Component 5 Player decisions.

3.    Component 5 Player Decisions by Fielding Position
The breakdown of Component 5 Player decisions by fielding position is as follows:

Position 1921 - 2018Since 2000
Pitcher 5.6%4.8%
Catcher 1.0%0.8%
First Base 7.0%7.3%
Second Base 15.6%15.7%
Third Base 15.4%15.2%
Shortstop 18.3%17.1%
Left Field 12.5%12.8%
Center Field 12.4%13.0%
Right Field 12.3%13.3%

For older years (typically, pre-1974), there is less information on the first fielder to field hits and, in some cases, there is even uncertainty on the fielder(s) involved in some outs on balls-in-play. These will lead to less reliable fielding records in general, although it is not clear to me that this would affect the distribution of fielding plays for those plays which can be identified.

Excluding pitchers and catchers, the numbers look like this:

Position 1921 - 2018Since 2000
First Base 7.5%7.8%
Second Base 16.7%16.7%
Third Base 16.5%16.1%
Shortstop 19.6%18.1%
Left Field 13.3%13.6%
Center Field 13.3%13.8%
Right Field 13.2%14.1%

Most of these results look reasonable: catchers handle very few balls in play (and most of those that they do handle require relatively little skill on the catcher's part), and middle infielders handle more plays than corner infielders. One result does strike me as a little bit curious: corner outfielders earn somewhat more Component 5 decisions than center fielders. This is explored elsewhere.

Component 5 leaders are shown here.

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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