He was very poor but I think it's harsh to say he'll crumble, or to single him out as a confidence player - almost every attacking player is a confidence player to some extent. Bale had a terrible run of form after his move but there's a reason both us and Spurs were in for him, he was talented. He is talented.
I'd back Johnson if he were in my team though, he's got a beauty and versatility to his play Bale won't ever have, so if he does bring it all together it'll be the makings of a fantastic player. Bale's devastating and has the ability to single-handledly rip apart a defence, and he's an excellent defensive asset in terms of balance and cover, but he's not got a lot of variety to his game I don't think. With the way he's playing he won't need it to become a very good player, but I'm not sure about him at the very top level. Champions League will be a good indication though, if he does well then he could make a big name for himself on the continental stage.
I'll admit I wasn't all that impressed by Johnson the few times I'd seen him for the u21s and 'Boro before he went to City, but he's shown a type of class on the ball that you'll never tire of watching and one that is so rare it's almost unique in British wingers. He's not just a great driving dribbler with a strong shot, like Bale, but he's got excellent close control and, more importantly, an eye for a pass. He's still got inconsistency in his game to the extent that Bale doesn't have(any more), but he's got a level of potential above him, I think.
Still, Bale might well be the better player because he knows how to use his assets, we've seen that, but if Johnson does the same he can be a star for club and country at the top level to the extent I can't see Bale reaching.