CHillTennis
Hall of Fame
As I remember, Del Potro was healthy in 2013 (in fact it was one of his better years), yet lost to Hewitt in the second round. I would say it's safe to say he wasn't beating Nadal or Djokovic in this tournament.
I don't even need to mention USO 2018 in order to claim his head to head against Djokovic is totally one sided. I don't care how many times their matches looked close, what matters is that Djokovic always wins in the end. It's like the Federer-Wawrinka matchup, where you knew 99% of the time who would win it, doesn't matter how "close" it looked. So if Djokovic beat Wawrinka in USO 2013 semifinal, surely I would expect him to beat Del Potro, even if it would take 5 sets.
RG 2015 is just not serious to even discuss. He would need someone to take Djokovic out for him, and even if that somehow happened, I wouldn't favor him against Wawrinka. And most likely, he just loses to someone of Hewitt's level in an early round again. One pretty strong run in 2009 (and even there he ended losing the last two sets 6-1 6-4) doesn't make him some beast on clay.
He lost a year out of his career due to the first wrist injury that he sustained in 2010.
In my opinion, he was never the same.
Even during that period of time when he was playing well in 2013.
It wasn't the same level as his 2009 US Open.