I don't think players make players better at all. I think coaches make players better and scheme could make players better, but players are already good at what they do, they just need the right mix of scheme, coaching, and talent around them. Steve Kerr could always hit a knock down shot, but he couldn't do it as much when he didn't have Jordan over there sucking up all the attention.
Terrence Williams couldn't do squat when he didn't have Dez Bryant over there sucking up all the attention. Sometimes, players need other players and better scheme to show off what they can do. And by the way, Williams never won anything but regular season games, so I wouldn't necessarily call Williams a great player, he was what most receivers are. If he elevated the team to Super bowls, then I could sing his praises.
If a QB can't throw, your receiver will look pedestrian. When he's changed out for a QB that can throw, he'll look like what he's supposed to look like. But he also needs the right scheme, because if the scheme does not direct the QB to throw it to him, or he's running routes not conducive to his talents, he still won't succeed. Lot's of variables go into the success of a player, and not just saying, this player made this player look good. And this is coming from an ex football player, and not some guy sitting on his couch being a paper coach/owner/gm and scout.
So this players making other players great is a crock. You're either good or you're not. But you have to give players a true chance to prove it.