That's the only advantage of Spence, lol.. I'm maybe a little bias here but if Spence could not hit Pacquiao with clean shots, Pacquiao will be able to maintain his stamina and he will win the fight. Well, I would not think a lot, I would still bet on Pacquiao to win because the odds are very attractive.
Opening Odds are really attractive in favour of Pacquiao with +350 considering the chances for Pacquiao to win the match is not quite low.
Spence for sure doesn't want to underestimate the post prime Pacquiao like Thurman did. He'll probably be intimidated until he doesn't test Pacquiao's punch first.
It has been 2 years since Pacquiao last fought, but he said in the interview that he isn't worried about the length of time he spent without any fight because his body needs more time to recover as he aged, but the conditioning is much better than the last fight. So, I guess he's more than ready and that means he's still got a lot of gas in his tank.