Component 7: Ground-Ball Double Plays

In the seventh step of calculating Player Wins and Losses, batters, baserunners, pitchers, and fielders are given credit and blame for whether or not ground-ball outs become double plays in potential double-play situations.

1.    Calculation of Component 7 Player Game Points
Component 7 comes into play when ground-ball outs are recorded in double-play situations ¢ defined as a runner on first base and fewer than two outs. Offensive Component 7 games are split between the batter and the baserunner on first base. Defensive Component 7 games are split between pitchers and fielders. Fielding Component 7 games are split between the fielder who starts the initial play and the potential pivot man on the double play.

2.    Division of Component 7 Game Points Between Pitchers and Fielders
Component 7 Player Games are shared between batters and baserunners, and 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.

For Component 7, decisions allocated to fielders are split evenly between the fielder who starts the initial play and the pivot man. In the latter case (the pivot man), such a fielder only receives Component 7 credit/blame if he is involved in the play. That is, on a ground ball to the shortstop, if the baserunner on first is forced out, 6-4, then the second baseman would be considered the pivot man in this case and would share some Component 7 credit/blame based on whether he was able to complete the 6-4-3 double play. If, however, the shortstop simply threw directly to first for the 6-3 out, then all blame for failing to turn the double play in that case would fall on the shortstop.

To summarize the process for dividing Player decisions, one measure of the extent to which a particular factor is a skill is the extent to which a playerÆs winning percentage persists over time. To evaluate the persistence of skills, I fit a simple persistence equation which modeled Component 7 winning percentage on even-numbered plays as a function of Component 7 winning percentage on odd-numbered plays:

(Component 7 Win Pct)Even = bĢ(Component 7 Win Pct)Odd + (1-b)Ģ(WinPct)Baseline

where (WinPct)Baseline represents a baseline winning percentage toward which Component 7 winning percentages regress over time. Equations of this type were fit for Component 7 Player Game Points for batters and baserunners as well as for pitchers and fielders. Separate equations were estimated for each infield 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 7 Winning Percentage: Catcher
```
Pitchers:  n = 1,449, R2 = 0.0002

WinPctEven = (9.74%)ĢWinPctOdd + (90.26%)Ģ0.5000
(3.639)

```
```
Catchers:  n = 2,337, R2 = -0.0158

WinPctEven = (4.50%)ĢWinPctOdd + (95.50%)Ģ0.5000
(1.937)

```
Component 7 winning percentage is considerably more persistent for pitchers than for catchers. This leads to a split of Component 7.2 decisions of 68.4% to pitchers and 31.6% to catchers.

Persistence of Component 7 Winning Percentage: First Basemen
```
Pitchers:  n = 20,624, R2 = -0.3495

WinPctEven = (86.19%)ĢWinPctOdd + (13.81%)Ģ0.5000
(238.9)

```
```
First Basemen:  n = 6,143, R2 = -0.1435

WinPctEven = (44.69%)ĢWinPctOdd + (55.31%)Ģ0.5000
(40.20)

```
As with catchers, the persistence coefficient here is stronger for pitchers than for fielders. The Component 7.3 decision splits are 65.9% to pitchers versus 34.1% to first basemen in this case.

Persistence of Component 7 Winning Percentage: Second Basemen
```
Pitchers:  n = 26,235, R2 = 0.0001

WinPctEven = (-1.07%)ĢWinPctOdd + (101.07%)Ģ0.5000
(-1.761)

```
```
Second Basemen:  n = 7,063, R2 = 0.0437

WinPctEven = (21.76%)ĢWinPctOdd + (78.24%)Ģ0.5000
(19.02)

```
Unlike with catchers and corner infielders, Component 7 winning percentages are more persistent for second basemen than for pitchers. Based on these results, Component 7.4 Player decisions are divided -5.2% to pitchers versus 105.2% to second basemen.

Overall, Component 7 accounts for 17.1% of all fielding decisions by second basemen.

Persistence of Component 7 Winning Percentage: Third Basemen
```
Pitchers:  n = 2,230, R2 = -0.1254

WinPctEven = (0.31%)ĢWinPctOdd + (99.69%)Ģ0.5000
(0.131)

```
```
Third Basemen:  n = 2,566, R2 = -0.0382

WinPctEven = (-1.13%)ĢWinPctOdd + (101.13%)Ģ0.5000
(-0.575)

```
The split of Component 7 decisions for third basemen is similar to that of first basemen, with third basemen receiving 138.1% of the credit for double plays in which they are involved.

Persistence of Component 7 Winning Percentage: Shortstops
```
Pitchers:  n = 23,139, R2 = -0.0021

WinPctEven = (-1.27%)ĢWinPctOdd + (101.27%)Ģ0.5000
(-1.897)

```
```
Shortstops:  n = 5,853, R2 = 0.0259

WinPctEven = (17.74%)ĢWinPctOdd + (82.26%)Ģ0.5000
(14.07)

```
As with second basemen, Component 7.6 player decisions are credited more heavily to shortstops than to pitchers. Component 7.6 Player decisions are divided -7.7% to pitchers versus 107.7% to shortstops.

Component 7 is a somewhat less important component of shortstop defense than for second basemen, accounting for only 13.5% of all fielding decisions by shortstops.

3.    Impact of the Baserunner on First Base on Double Play Ground Balls
Component 7 Player Games are divided between pitchers and fielders based on the extent to which player winning percentages persist across different sample periods as outlined above. A similar analysis was undertaken to see if the baserunner on first base had any apparent influence on Component 7. Persistence equations were estimated for batters and baserunners. The results were as follows.

Persistence of Component 7 Winning Percentage
```
Batters:  n = 45,385, R2 = 0.0341

WinPctEven = (19.72%)ĢWinPctOdd + (80.28%)Ģ0.5000
(42.40)

```
```
Baserunners:  n = 41,520, R2 = -0.0165

WinPctEven = (3.38%)ĢWinPctOdd + (96.62%)Ģ0.5000
(6.830)

```
The persistence coefficient is much stronger for batters (19.7%) than for baserunners (3.4%). Nevertheless, the persistence coefficient in the baserunner equation is significant with a t-statistic greater than 2. Based on this, I divide offensive credit/blame for Component 7 decisions between batters and baserunners. Batters are given 85.4% of the credit here, which is equal to the batter persistence coefficient, 19.7%, divided by the sum of the two coefficients (19.7% + 3.4%). Baserunners are credited with the other 14.6% of offensive Component 7 player decisions.

Component 7 leaders can be found 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.