Maybe.
Or maybe, Mitch's ceiling is a 10, and he's practiced at an 8, and he's played at a 4.
Streveler practices at a 7
Perra practices at a 5.
It sounds like you are arguing that CS and Perra must be practicing at a 3 since they can't supplant Mitch. But as I showed, it could be that Mitch is just not playing to his capability in games, and they don't want to pull the plug on him and would rather give him some time to figure it out. Maybe streveler performs better than Mitch vs tcu(hard to be worse), but over the year, Mitch would end up winning 8 and CS wins 6.
Just using examples of how your statement that this is proof of anything is wrong. You may be right and you may not, lots of variables and possibilities.