One thing that has changed this year is that many batting cameras have been updated with wide-angle views (which I think is a questionable thing to do, for those gamers who have trained their eyes over the years to a specific camera), so the perception of how the pitch travels toward the place has changed a bit. In particular, I think it has an effect of making it harder to distinguish the pitch speed right after the release (because the apparent movement of the ball on the screen has become smaller).
I think some of what people are talking about as to how the pitch speed seem to be off this year is due to the change in cameras.