I mean, not sure if you want a serious answer, but obviously that's not how any player would view it. I'm sure Brandon feels that he and his teammates should be able to play well and win games regardless of what Manning or anyone else does, and I'm sure he's disappointed and frustrated with himself when that doesn't happen. I can't imagine they view something they've put so much work into as a "lost cause". Also, I think most players tend to underrate the impact of coaching and put most things on themselves as far as how games turn out, for good or bad.
As an aside, Brandon and the rest of our guys repeatedly taking ownership for losses is one of the hardest parts to watch of all this for me. From our point of view its clear that a lot of the things going wrong are primarily not their fault, but I doubt they are able to see it that way and instead are probably extremely frustrated and hard on themselves. Regardless of how you feel about him as a player, by all accounts Brandon is a good teammate and leader, and for him to be in this situation of perennially losing with too much expected of him sucks.