The Floyd claim about drugs was in 2009 after Pacquiao beat Miguel. So he looked impressive for 2 fights after that against Clottey and Margarito. You also have to look at Pacquiao's style when you assess his stamina. A high activity in and out fighter like Manny will age a lot quicker than say a pure boxer. It takes huge amounts of stamina to do what he does and unfortunately he is ageing e.g. Tyson, a come forward pressure fighter, aged a lot quicker than the pure boxer Lewis. Actually, in his welter debut he threw 585 punches in 8 rounds. That is a pretty damn high work rate. He also fought 3 minutes of every round against Rios. Not to the same level he once did but his stamina was not in question in that fight. It's really only the Bradley fight where he took time off because Pacquiao found his style awkward to deal with; even though he won both fights convincingly.