Seppi had his results for the very fact that he is passive and very 'tidy/neat' in his game style which is poison for players like Verdasco and Paire. As for the two sets against Djokovic, I think everyone in here agrees on the fact that DJ never looked in trouble and went down mainly beacuse he was missing a lot of shots. Other slams he went out R1 to Gasquet in four sets, R1 Istomin 5 sets (he could have won) and R1 to Robredo in straights sets (...). Not so much impressive if u ask me.
As for Monfils we are saying the same thing, he should have ballbashed since he was quite tired. otherwise running 10km in every point doesn't help at all.
Seppi is solid and not spectacular made the most of his abilities that's all anyone can ask of a player. Verdasco, Mathieu those guys have very good records against him, don't be FiloV do some research. Monfils was 4-0 before today, those guys can hit through him and his 2nd serve is the big weakness.
His Slam results have no relevance to his match. Unseeded at AO, so how many were beating Djokovic on clay this year not many players. He has never done well at the US Open and never will. Won a total of 3 matches there since 2004.
You must not have watched him at all this season, if you haven't see the improvements. He actually goes for it on the forehand side when he creates the chances, constructs points well since he doesn't have a big weapon he has to play like this.