How to explain Brian Bannister

Day vs NightWell, I’m not going to tell you I can explain him because I can’t. However, I can shed some light on exactly how strange his “day vs night” record is. In case you were not aware, he is 3-0 (0.90 era) by day and 2-3 (5.56 era) by night this season. For his career, he is 15-4 in sunlight and 13-25 by moonlight. That’s a radical difference which simply cannot be attributed to random chance.

I decided to prove that random chance was a statistical impossibility so I wrote a program to just that. Since Bannister’s overall record is basically 50-50 (technically 28-29), I let the program randomly pick a number between 1 and 10. If the number was 5 or less, I gave him a win. If it was 6 or more, I gave him a loss. Since he has 19 day games, I wanted to know how often (by chance) he would have 15+ wins and only 4 (or less) losses.

I ran the program one million times. Assuming a pitcher is a .500 pitcher, the odds of randomly having 15+ wins in 19 games is .0096 – or just under 1% of the time.

I did the same thing based on 38 night games. What percentage of the time would a .500 pitcher only have 13 (or less) victories? The answer is .0364 – or 3.6%.

Therefore, what are the chances that both could be true at the same time? Well, that’s as simple as multiplying them times each other. Thus, the probability that Bannister could be 15-4 and 13-25 purely by random chance is .0003503 – or roughly 3 one-hundredths of a percent. In other words, there is virtually no chance that it is by chance.

Now that we can safely attribute it to something in his make-up, it’s a fair question to ask what’s the reason? As I say, I don’t know. I presume he doesn’t either. The only thing I do know is that if I’m Hillman, I do everything possible to control the schedule such that he pitches during the day and not at night. He’s scheduled to pitch Saturday at 3:10 pm (day game). Great! But, let’s suppose it was a Saturday night game. He’d still be scheduled to pitch. Screw that!

I can’t imagine it would make that much difference whether Meche pitched on Saturday night or Sunday early afternoon. But, if it is a problem slightly manipulating Meche’s schedule, then put Banny between Davies and Hochevar. If you do that and you have to adjust the schedule forwards or backwards, you aren’t affecting Greinke or Meche. Considering the radical difference in his abilities during the day versus night, that’s the least you should be doing as a manager IMO.

While I’m on the subject of 2009 KC starting pitchers, here are their career day/night records. Shown are their day, night and percent differential just to give you an idea how strange Bannister is. For example Bannister’s day win% is .789 while his night win% is .342. Therefore, the differential is .447.

Hochevar has too few daytime games to show results.

It’s pretty easy to see how radically different Bannister is from the rest of the KC starters.

Naturally, the question that is begging to be answered is whether or not there is another Bannister in the majors somewhere. Although it was ridiculously cumbersome to find out the answer, I looked at every starting pitcher in the majors this season who has started at least five games in 2009 with at least 30 decisions in his career. That’s 114 pitchers.

Shown below are the pitchers with the biggest differentials between day and night winning percentages.

If you eliminate everyone that doesn’t have at least 57 decisions, this is what you are left with.