So, once you have all the data to hand, slicing and dicing is the easy part. Remember how we compared the Nats' 2009 run expectancy to the NL average yesterday? Well, here's the AL average, just for laughs:
| Runners | no out | 1 out | 2 out |
| --- | 0.53 | 0.29 | 0.11 |
| 1-- | 0.91 | 0.53 | 0.23 |
| 12- | 1.54 | 0.91 | 0.45 |
| 123 | 2.33 | 1.60 | 0.75 |
| 1-3 | 1.88 | 1.23 | 0.53 |
| -2- | 1.14 | 0.67 | 0.33 |
| -23 | 2.03 | 1.43 | 0.56 |
| --3 | 1.43 | 0.92 | 0.34 |
Right off, we can see that AL teams score an average of 0.53 runs per inning versus the NL average of 0.48--just what you'd expect from the cheater training wheel league! A review of the NL table and comments after the jump.
Recall the NL average run expectancy:
| Runners | no out | 1 out | 2 out |
| --- | 0.48 | 0.26 | 0.09 |
| 1-- | 0.83 | 0.51 | 0.21 |
| 12- | 1.39 | 0.88 | 0.41 |
| 123 | 2.12 | 1.45 | 0.66 |
| 1-3 | 1.64 | 1.13 | 0.48 |
| -2- | 1.09 | 0.65 | 0.28 |
| -23 | 1.95 | 1.35 | 0.52 |
| --3 | 1.19 | 0.95 | 0.37 |
The AL scores about 5-10% more runs on average in any given base/out situation. Oddly, the only situations where the NL does better is when there's a runner on third with one or two outs: those situations happened roughly a thousand times (or more) in each league in 2009, so it doesn't look like a "small numbers" fluke. I also went through and added up the number of times each league was in each situation to see if there were interesting patterns (these are all expressed as a percentage of total PA for the league):
| Runners | AL | NL |
| None | 54.9% | 54.9% |
| RISP | 26.8% | 27.2% |
| Loaded | 2.7% | 2.8% |
| First | 18.3% | 17.9% |
| Second | 8.5% | 8.9% |
Both leagues came to bat with the bases empty and the bases loaded about the same amount of times, although the NL came up with RISP slightly more often. NL batters had a runner on second more often, while the AL had a runner on first more often--again, the differences aren't that large. Still, I thought it was neat, even if I don't know what it means.
See any deeper insights? Put 'em in the comments! One more, and then we're done with run expectancy until the AS break.