It's not only Nadal who got a tough draw but everyone on this half has it tough as well, so I want to make that clear. We can't look at things as if there's only one player who got it tough and overlook all other aspects of things.
Andy's draw is tough too. He has a couple of okay rounders but given that he's not as confident post-surgery and not as match-fit, even these two rounds may become handful. Then he's got Lopez who gave him really tough time at 2012 USO. Same goes for Isner (2011 USO - in fact, that match took so much out of Andy that he didn't have enough left in the tank to go toe to toe with Nadal in the semi.)
After this point, he will have to play the other 'big three' to win the tournament. Same goes for Federer as well. Nadal may not and perhaps will not face rest of the big three in succession, though I take it Delpo isn't going to be easy if he makes the qtr. So as I see it, all the top guys on this half have it tough especially from qtr final on.
Andy's possible draw:
R1: Go Soeda
R2: Qualifier
R3: Feliciano Lopez
R4: John Isner
QF: Roger Federer
SF: Rafael Nadal
Final: Novak Djokovic
Another thing to take into account is the fact that, the draws will not pan out the way it looks on paper right now. Both Federer and Murray may not make it. Heck, even Del Potro may not make it as he tends to start slow and often find himself in a great deal of trouble, so it may all open up for Nadal who knows.
Though albeit, I will be hoping for Murray to go as far as possible and maybe win the title. He can definitely play into the tournament and get in-form. I remember an out of form Berdych got as far as the semi at 2012 USO. It has happened many times with players in the past. In Berdych case back then, he saw Federer and Murray in his half and he felt he could take out at least one of them and he got motivated by it. Andy could do it too if the draws open up or feels the same and if he makes AO as his target (and not players) and slowly moves towards it. At least this time there's no pressure and no expectations.
Nole's got Wawrinka in the qtr so that's going to be handful and also, Ferrer has the tendency to drain people though Nole is quite aggressive from baseline and perhaps won't let Ferrer do that but still, out in the sun in this heat, it's not going to be a pushover as I see it.