Not sure I understand why you're dismissing the mental side of the game of basketball.
Why is it that good shooters (recall Cooney, GMAC) lapse into extended shooting funks? Or why free-throw shooters hit them in practice, but miss them when it is crucial for the team to pick up points late in the game? Why does pressure get to some players late in the game but not others?
Specifically, if confidence is such an important factor---and JB agrees that it is---then how is a player supposed to summon up some confidence after he has missed his last three shots? What is that ideal mental attitude that a top-performing athlete needs to carry into a game in order to excel?
For some players, fixing their problems with confidence can be especially vexing, since it is comparable to the challenge of trying "not to think about a pink elephant." The more you try not to think about it, the more you think about it. Thus, my 'advice' on how one might be able to escape that mental trap.
Seeing Tyus' frustration---at the same time that Brissett is playing like an all-American---makes me wonder if his anxiety about his game performance could end up becoming a 'thing' in his mind, that could end up hurting his performances throughout the season.
I get it that you're not accustomed to this kind of analysis being proffered on a fan discussion board, but why go out of your way to characterize it as something different, as a type of speculation that represents something other than perfectly legitimate analysis?
Seriously, if you didn't find anything in my comment that is worthy of your time, then why not simply move on to another comment?