After this search, I wanted to investigate larger sample sizes to see if I could find anything interesting. I no longer wanted to look at particular teams, but rather the MLB as a whole. Do batters hit better in particular situations? I used the Play Index to check league-wide batting average since 1960 (more than 50 years of data, a huge sample size) for each different combination of bases occupied.
Description | State | BA |
No runners on | 000 | 0.256 |
Runner on 1st | 100 | 0.276 |
Runner on 2nd | 020 | 0.247 |
Runner on 3rd | 003 | 0.277 |
Runners on 1st and 2nd | 120 | 0.254 |
Runners on 1st and 3rd | 103 | 0.294 |
Runners on 2nd and 3rd | 023 | 0.270 |
Bases Loaded | 123 | 0.279 |
All states | --- | 0.261 |
Intuitively, having more runners on base should lead to a higher batting average. Why? Well, mostly due to selection bias. Simply put, selecting states in which a pitcher may be struggling (more runners on base) should result in better performance by the batter, even if the batter isn't actually any better. In addition, based on traditional lineup construction, good hitters should get more opportunities with runners on base than average or poor hitters. For the most part, the table above supports this argument. With no runners on base, the batting average is .256, and if we combine the other 7 states, the batting average with at least one runner on base is .268, a 12 point increase. However, breaking down the individual states paints a different picture. If more runners correlates with a higher batting average, then why is the batting average with runners on 1st and 3rd (.294) significantly better than the batting average with the bases loaded (.279)?
As it turns out, adding a runner to second base always decreases batting average. To see this effect, we can arrange the 8 baserunner combinations into pairs to isolate the effect. Each pair includes an initial state without a runner on 2nd base and the same state with a runner on second base. In all four cases, the batting average is worse with the extra runner on 2nd.
Conversely, adding a runner to either 1st base or 3rd base always increases batting average. Similar to the table above, we can isolate the effect in each case. Adding a runner to first base increases batting average by 7 to 20 points:
Initial State | BA | Added runner on 2nd | BA | Difference | ||
No runners on | 000 | 0.256 | Runner on 2nd | 020 | 0.247 | -0.009 |
Runner on 1st | 100 | 0.276 | Runners on 1st and 2nd | 120 | 0.254 | -0.022 |
Runner on 3rd | 003 | 0.277 | Runners on 2nd and 3rd | 023 | 0.270 | -0.007 |
Runners on 1st and 3rd | 103 | 0.294 | Bases Loaded | 123 | 0.279 | -0.015 |
Conversely, adding a runner to either 1st base or 3rd base always increases batting average. Similar to the table above, we can isolate the effect in each case. Adding a runner to first base increases batting average by 7 to 20 points:
Initial State | BA | Added runner on 1st | BA | Difference | ||
No runners on | 000 | 0.256 | Runner on 1st | 100 | 0.276 | 0.020 |
Runner on 2nd | 020 | 0.247 | Runners on 1st and 2nd | 120 | 0.254 | 0.007 |
Runner on 3rd | 003 | 0.277 | Runners on 1st and 3rd | 103 | 0.294 | 0.017 |
Runners on 2nd and 3rd | 023 | 0.270 | Bases Loaded | 123 | 0.279 | 0.009 |
And adding a runner to 3rd base increases batting average by 18 to 25 points:
Initial State | BA | Added runner on 3rd | BA | Difference | ||
No runners on | 000 | 0.256 | Runner on 3rd | 003 | 0.277 | 0.021 |
Runner on 1st | 100 | 0.276 | Runners on 1st and 3rd | 103 | 0.294 | 0.018 |
Runner on 2nd | 020 | 0.247 | Runners on 2nd and 3rd | 023 | 0.270 | 0.023 |
Runners on 1st and 2nd | 120 | 0.254 | Bases Loaded | 123 | 0.279 | 0.025 |
The point with these last two tables is not to prove, somehow, that a batter suddenly becomes a better hitter with runners on base. As discussed earlier, a large part of this increase is probably due to selection bias. But, it does seem logical that adding a runner to second base should also exhibit this effect, and the magnitude of the increase should be somewhere in between the effects shown for adding a runner to 1st and adding a runner to 3rd (maybe about 10 to 15 points in batting average). In reality, the effect is quite the opposite (7 to 22 point decrease).
Is there any logical explanation for the data? Conservatively, hitters are about 20 to 25 points worse in terms of batting average with a runner on 2nd than what we might expect. I believe that this effect is almost entirely due to the distraction of having a runner directly in the batter's line of sight. While the batter is trying to concentrate on the pitcher's delivery, release, and the trajectory and spin of the the ball, he has to cope with a teammate dancing around next to second base behind the pitcher. Even if the batter tries to "block out" the runner, it almost certainly has an effect that cannot be muted. The effect seems to be worse if a runner is on 2nd base and 3rd base is open, as the two worst batting averages are with a runner on 2nd (.247) and with runners on 1st and 2nd (.254). In these cases, the baserunner at 2nd probably moves around more since he is the lead runner and can possibly steal 3rd or take off early to score on a single. Is there anything that can be done to mitigate this "distraction" effect? Maybe if you're David Ortiz and you just hit a leadoff double, you should think about taking a lead and then standing still until the ball is hit.
This has me wondering what the effect is when second base is stolen, for instance if it is stolen late in an at-bat is the decreased AVG effect less than if it's stolen early.
ReplyDeleteConversely it seems there is an extra reward potential in attempting to steal third because the batter's chance for a hit may have just increased.
--Lance
What I'd really like to know is what amount of the gain from runners on 3rd come from sacrifice flies saving batting average. I think it's a relatively small effect, perhaps adding 20% extra value, which doesn't make it particularly interesting. Still, the sac fly effect unfairly biases towards runners on 3rd.
ReplyDelete--Lance (again)