are you serious? Wayyyy past his prime hewitt took a set off of novak at his BEST SLAM in his PEAK PERIOD!I've seen Hewitt play in his prime. Of course he's good on grass. It's his best surface. Heck, I might even favour him against Djokovic in a best of 3 format.
But in Wimbledon, Best Of 5.....different kettle of fish. Hewitt, even at his best, would struggle to take a set off post 2011 Novak at Wimbeldon.Prime Djoker would just be too much for Hewitt at a slam. Any slam.
Del Potro is a streaky, inconsistent player and always has been. On his day, he can beat anyone in the world on fast surfaces (though he's a hardcourt specialist). But he can also have baffling losses to players he shouldn't be losing too. It's impossible to know which Del Potro will turn up. I wouldn't read too much into even old Hewitt beating him in a best of 3 tune-up event.