Fun movie if you haven't seen it. Seems to support that top end hasn't changed but average velocity probably has
I am told by a very reliable source (Former D1 20 year Coach) that what has changed is the gun used to measure velo. "Back in the day," 80's-90's, you had the Jugs & the Ray. The difference between the 2 was that typically, the Jugs would read the velo at a closer proximity to release while the Ray was roughly velo at the plate. The swing was typically 3-4 mph with the Jugs having the higher reading. Now it seems to be the Stalker which I understand tags velo at release & has a higher reading than the Jugs.
This Coach told me he has kept all of the guns they used going back to the 80's & the readings today with the Stalker are definitely "inflated" compared to the prior tools used to get readings.