No it dont. Armstrong was beating top WW's whilst weighing in as a LW. its safe to say he was better at FW and LW than at WW. It just so happened he was that good, he can still be good at WW despite being at a size disadvantage. For the record, p4p MAB was much better than Cotto...and that was at 126, and Pac beat MAB worse than he did Cotto.
140 is his natural weight and he would probably crush all opposition at 140, 147 is where most of the money is at.