Tuesday, August 13, 2024
Leadoff Walk v Single?
A walk is as good as a hit, is essentially a true statement when the bases are empty. Which has been true for most of baseball history (with the exception being the extra inning placed runner, the XIPR).
In a Markov chain, the presumption is how you entered a state is immaterial. Being in a state is the information you need in order to know what's to come. So, if you have a runner on 1B with 0 outs, does it matter HOW you got there? If it doesn't, then that's your Markov state: runner on 1B, 0 outs. If it DOES matter, then your Markov state has to include how you go there, so that your actual Markov state is 1B-or-BB-or-HBP-or-Err, and the runner on 1B and 0 outs.
In an award-winning presentation at SABR52, Bailey Hall tackled that issue. The main overall point is that the number of runs that followed the runner on 1B, 0 outs state was essentially the same, regardless as to how the state was entered (0.94 to 0.93 runs following a leadoff BB or single respectively). But, Bailey did note that there may be a pitcher-by-pitcher effect, that maybe some pitchers are more affected by one or the other, and maybe even at the inning-level.
Most important to all this is that the question was asked, a solution has been offered, and the presentation is beyond outstanding (with pure baseball themes wherever you look). This is what an #AspiringSaberist should do: ask the question, roll up their sleeves, and show off the work. Because others will be watching, and they will remember any good work.
(click to embiggen)