He's a beneficiary as much as a victim of his era. The drop off in talent after Fed-Murray-Nadal-Djoker, the collectively slower surfaces overall. You can ask if he'd win a Slam in another era, but you should also ask if he could be a Top 5 player making a bunch of Slam QFs and SFs in another era.
He's a great player, no doubt, but I don't see him winning Slams in any other era. As someone pointed out, Chang could only muster one Slam.