I'm not going to defend Trey Lance or bash him, because he's an unproven. No it doesn't look good that Shanahan moved on from him, but he's only played in 8 games and was 5 TDs and 3 INTS which isn't all time terrible for first 8 starts, but not great either. We don't know who he is yet because he wasn't given enough of a chance. The only reason he's on our roster is the 49ers struck gold with the last pick in the draft and they only found out because he got injured.
But Dak has had plenty of chances to shine. It would not be an all time blunder if you start Trey Lance and we go 2-15 to me, because I don't care about regular season wins. We know Dak will fail in the playoffs so I'm doing an American Idol audition for the next Dallas Cowboys QB, if Trey Lance fails we look for another one.
This is the way I see it, but I know it's way more likely that the Cowboys cave into Dak's demands and he's the QB for at least the next 5 seasons. And when he's 36 we're still at 5 Super Bowls but won some more divisions, big whoop. Doubtful he ever gets past the Divisional Round, zero proof he is capable of doing so and QBs don't just suddenly change in their 30's.