Well, wake-up is a situation that makes it easier to reversal. The player knows exactly when he must do the move and with anticipation, so he does not need to rush anything. I consider myself particularly bad with reversals, but on a good day I can get most of them when waking up. Most times I mess them up are due to not being used to the controller: I mess up the motion, not the press.
As for the question itself, I’d ask back if they were all with the same strength. There is only one player I know who does single button reversals with consistency, which is dg (a Brazilian player, not Dark Gaiden from Cali). I’ve watched his replays and played him with Input Watcher and could verify he was just that good with timing that single button with a single press. A number of others use turbo, being that some of them admit. Finally, answering the question, if the reversals are all with the same best strength (jab for Ryu and Ken, short for Guile, roundhouse for Chun) then I would be really suspicious, as it is something VERY hard to do. If each time you notice a different version, then they may be pianoing.
PS: I have translated 50% of my article about button pressing. Hope to get it done tomorrow or next Monday.