A quick one as we work up another, more elaborate "tale of two-dimensionality"...
Ever wonder just how often baserunners go from first to third on a single? Score from first on a double? Score from second on a single? Or are you the type that would rather focus on individual data, a la TOOTBLAN?
Not that TOOTBLAN isn't worth some of your time. However, there's more to baserunning than just how often players get thrown out. (This is another area where Bill James pushed folks down a particular path only because the data was suddenly so easy to compute...he's had more than his alotted share of these moments.)
What we need are some benchmarks. Forman et fils take us part of the way with their presentation of baserunning advancement data; they decided to lump all advancement together, though, despite having enough detail in the three separate advancement categories mentioned above.
By collecting, collating, and averaging these three advancement categories, we can see if things like run-scoring levels, increases in home runs, etc. are having an effect on how often baserunners take extra bases.
And our chart at right suggests that it's a kind of "split decision" (you know, the ones that make boxing fans suspicious). It turns out that there's been a noticeable decline in the percentages for going from first to third and from second to home on a single (red line and purple line respectively).
Going from first to home on a double, however, has gone through some downs and ups but is currently quite close to the frequency that was in place back in 1982 (remember, these are four-year averages, and "1982" refers to the years 1979-1982; "2014" refers to the years 2011-2014).
(Note that these figures are the decimal equivalents of percentages: .700 at the top means 70%, etc.)
So what's causing it? High run scoring? Complacency? More aggressive outfield play? The vagaries of globalization?? Hard to say. But it's clear that baserunning has become more conservative over time. Whether consistently lower run-scoring levels will eventually affect these trends is something about which we'll simply have to "wait and see." The trend lines are pointing slightly up. We can only hope, of course--the fact of the matter is that this is another indicator of the game's creeping rapprochement with two-dimensionality...and it really would be a good idea to reverse the trend.