I'm still surprised over how out of left field Browning being a top prospect has been, granted I haven't watched him near enough to form a proper opinion but when I watched one or two games he's featured in last year or the year before he didn't really stand out. It seems like he's really put some effort into improving his game over the past year or two and shown he wants to be a proper player, which suggests he's got a good head on his shoulders meaning he's probably got a good mental side to his game.
To be honest though I can just imagine that Bobby went up to him and said "Tyias, you're going to be ****ing boss. You know that right? Now go and tear the championship apart comprende?" and he just does a Forrest Gump and becomes boss because he was told to be.
...I have to admit to having a similar view, but sometimes things just fall into place. As you say, much of the game is about what is between a players ears and perhaps RM and others have given him a real confidence boost. Saying all of that, the boy is supposed to be a real athlete, and when you have that ammunition its a real help.