Let me start by saying I am a Lock agnostic. I have reservations about his maturity off the field and lots of reservations about his performance on the field.
But he hasn't played enough to show whether he can develop. The fact that the coaches said he was in a virtual tie for the starting battle with TB shows that in their evaluation, he has improved since last year. People who work hard and show improvement deserve a chance.
Starting Lock is really the only move that makes sense as we look forward for this franchise. TB has shown over the course of his career that he is not the kind of starting QB the Denver Bronco faithful are going to be satisfied with. Many fans knew that coming in to this season. TB has played enough games in this league to earn the journeyman backup label.
There is no downside to playing Lock the rest of the year. Playing Lock will fix our problems. If he plays poorly, we'll lose most of our games and get a high draft pick for his replacement. If he shows improvement, we won't need the high draft pick for a QB, and we'll likely win enough games that we won't have it anyway.
The most likely scenario if Lock starts is that Shurmer's ineptitude will hamper his development. If that is the case, so be it, we'll have a new QB in 2022 with a new set of coaches.
HOWEVER, playing TB has no upside either way. We are NOT a playoff team with TB. Period. So while we waste the year on playing a known backup that we don't want moving forward, we learn nothing about Lock's potential. We're just passing time, learning nothing for the future other than TB is not the QBOTF (something lots of fans knew three months ago).
While I expect Lock to be somewhat improved, but likely not enough to hand him the keys to the franchise moving forward, the best case scenario for the franchise is for him to ball out and be the QBOTF. That development would allow us to build the roster without spending big capital on a QB. I think the odds are small that that happens, but it has happened in the NFL before. If we don't play him, we throw that chance away and enter the offseason without the Lock question being answered, which would be really stupid.
That said, Fangio is going to be heavily biased against playing Lock, because he knows he's sitting on the burner. The interests of the organization are different from the interests of our failing coaching staff. I expect to see TB play until he's so injured he can't anymore. One thing Lock was good at was avoiding sacks. His sack% last year was 8th best in the NFL despite the OL struggles. TB is in the bottom third of the league this year and last year. Additionally, Lock had better 3rd down results and RZ results last year than TB is this year. He deserves a chance to show improvement in real action. The franchise deserves the chance to evaluate him once and for all. TB deserves to heal up.