oneupper, you're not nitpicking at all.
In fact, what you've stated is the conundrum I had when I was originally researching the data, especially how to handle the scenario that batters simply cannot walk on counts without three balls. I might add a column in the above charts also listing slugging percentage since walks have no bearing on slugging.
The main reason I went with the data on what happens on the actual count rather than after the count is it was much easier to collect overall league data so I'd have a basis of comparison (some of ESPN's stat splits haven't been working). There's a ton of tangents to branch out on relating to batter/pitcher counts, and that's definitely a key one.
Some other odd things I've sort of found ...
- All batters seem to hit very well with 0 or 1 strike in the count, even if the count is 0-1. Whether or not a second strike occurs seems to the biggest "what if" event in a plate appearance in determining likely hitting success, which ties into the data suggesting that the 1-1 pitch is the most important "swing pitch" in a plate appearance.
- Just glancing here, and with an admittingly small sample size, but there does seem to be a slight increase in slugging percentage as the count progresses from 0-2 ---> 1-2 ---> 2-2. Once the count gets to 3-2 there's a massive spike up.
- HBP happened about 2-2.5x more often when batters were behind in the count.
- Stolen base percentages in 2005 are higher when the batters are behind in the count: 72.4 percent when behind vs. 68.8 percent when ahead. This suggests that poorer basestealers may be taking some highly unnecessary risks attempting to swipe bags.
- GB/FB ratio when hitters are ahead in the count is 0.89 compared to a ratio of 1.14 when behind in the count. This makes sense since hitters see more pitches they can drive when ahead.
- GDP are only slightly higher when the hitter is behind in the count.
- Twice as many home runs are hit when hitters are ahead in the count than when hitters are behind in the count.