Better FHs on the run.
All the above makes sense. Yes, I have a better FH on the run, yes, I crowd my baseline ones and generally don't move much (flat-footed), I've just found out recently. But I just for some reason move really fast and hit harder w/ angles on the run! In fact, I surprised myself a few times after I did it. (Was it really me that moved that fast for that passing shot?)
Sampras' FH was like that too. His FH on the run was huge. Didn't he know about better positioning on the baseline? Of course he did, but his FH on the run (both on the baseline and straightforwards) was still way better.