Aside from his injuries, here are some other advantages that Federer and his extra years of practice has. There are quotes from former players, coaches and analysts:
Federer has had to work harder for his victories this fortnight. Why?
ESPN tennis reporter Peter Bodo: Call me a skeptic, or a grump; but in my experience, you actually can't have it all, at least not forever. And as much as I admire and respect Federer, and stand in awe of the way he's walked this triangular tightrope strung between career and family and age, it can't have lasted forever. The game is just too demanding. Federer is already in a kind of farewell tour mode, happily refusing to make the kinds of sacrifices he once made for career, and we're at the point where it's beginning to show. It's fine. He doesn't owe tennis a dime, and I hope he sticks around as long as he's having fun.
ESPN tennis contributor Simon Cambers: Two reasons. He's 38, and the conditions -- courts and balls -- seem to have been slower than ever. He's also played a couple of grinders in John Millman and Tennys Sandgren, who made life very hard for him, while his timing has not quite been there.
ESPN tennis analyst Darren Cahill: The conditions have been slower, much slower. It's also been cooler this year, so it's been much tougher to get the ball through the court. Most players have been saying it's harder to finish points; so for a guy who likes finishing points, it's been a more difficult tournament. He just hasn't been able to play that aggressive type of tennis.
ESPN tennis analyst Chris Evert: He played two hot players, so credit to them. Millman and Sandgren had no pressure and could go out there and just fire balls at Roger. They knew he wasn't as invincible as, say, five years ago. They all have a little bit of belief they can beat him, so their mindsets have improved and they just go out and play their best tennis. On the other hand, Roger has gone in and out a little bit. He's 38 and it's hard to have that intensity every single point when you've played for 20 years on the tour. The freshness factor is not there, at all. It's probably a combination. Mentally, Roger has probably lost a slight edge, and these other guys believe they can beat him. It's the same thing when players play Serena.
ESPN tennis analyst Brad Gilbert: Well, he's 38! He's actually had a great draw, but he's had to scrap. He found a way against Millman, but he was a little tired against Marton Fucsovics [in the fourth round] in the first set but found a way. I've never sat courtside and heard him grunting as loud as he was. Against Sandgren, you probably lose that match 99.999 out of 100, but somehow he found a way and that's the sign of a great player. The four most valuable words in tennis are "game," "set," "match" and your name. Everyone gets bogged down thinking it always has to be perfect, but sometimes it's not.