Nah, Ariza is just the middle man. He has connections with motor home labs who accidentally hit upon the secret compound while trying to develop a new variant of meth.
Timing. Sometimes you just get hit from not being 'scared' enough. It's happened to me. But usually it's a case, as in Pac-Margo, where more important things happen later on than eating an unanticipated jab. Maidana has better timing and countering ability than Margarito ever will. He is NOT a brawler, and has decent handspeed. It's not always easy to anticipate shots. There are little feints and movements that can throw someone off not even the audience seens. Also, good handspeed has nothing to do with defense.