The 49ers have a strong enough team where it really shouldn't make a difference whether Trey or Jimmy is starting. That Defense and Running Game + Kittle coming back should be enough for them to beat any body.
We all know what Jimmy is and to this point, it hasn't been enough. That's why they got Trey and why he was the starter, to let him grow so that he can eventually be THAT guy.
But the way Kyle used him excessively as a runner just left him vulnerable. The guy was running more than even Lamar Jackson did when he started out, while not being as fast and elusive as Lamar.
And Josh Allen, who is the one QB Trey is most often compared to, didn't run NEARLY as much as Trey did. Kyle didn't even give him a chance to show off his arm because he used him more as a Full Back, and now the kid just lost an entire season of his career, and now the team's long term future is in jeopardy.
So like I said before: FUCK Kyle Shanahan.