It isn't exactly fair to beat him to death with this, if they'd kept Barkley would their offense be better sure, would they be a good football team, no.
Barkley is having such a massive year because yes he's a great player, but also because he's now on a team that has other pieces around him that also work. It's weird how now on an offense with an average to decent QB with some weapons to throw to he's even more effective. Even better for him on the Eagles is he's still clearly the best offensive player.
If he'd stayed with the Giants it'd be the same old story they'd have run him into the ground again and teams would focus on him.