[Filthy Slider]

There is probably a way to test it out...for example, looking at a very large number of pitchers and comparing

IP at home vs. IP on the road
and then, looking for a correlation with the mean temperature of the home park.
Texas would be the easiest candidate to study...if one were to demonstrate that Texas pitchers (over a large sample) were able to pitch more innings in cooler stadium environments (i.e. most other stadiums) then it would give some statistical backing to the idea that hot weather causes pitchers to not have the same level of endurance as in cool weather.

Or, there's an easier way: keep track of how long you can jog on a nice cool day vs. trying to jog in 100 degree (F) heat....of course, that's not the statistical version, but I think it would give one a pretty good idea of how heat affects endurance.

And, my guess is that Markus' system of taking into account temperature probably isn't very nit-picky about a difference between, lets say 65 degrees and 75 degrees....it probably just rates something like 90 degrees as hot and something like 55 degrees as cool....that sort of thing...at least, that is, that's how I've seen in treated in other baseball sims through the years.