Is Juan Martin del Potro Back?

It was the upset of the day when Juan beat Stan Wawrinka (4) 3-6 6-3 7-6 (7-2) 6-3 on first Friday in Wimbledon. Del Potro is currently number 165th in the world, after missing almost 2 years due to wrist injury. We can see he has to drastically adjust his game, talking about backhand which is now generating very little topspin. He is also using a lot of one-handed slice shots, which works well on the grass but will most likely present a problem on all other surfaces.