It is difficult for us to evaluate Tebow's performance unless we have some agreement on the parameters.
He isn't a HUGE failure and bust if his only purpose was to divert the world from other patriot PR issues and to maybe, just perhaps allow Josh to develop a player to compete with Mallett, with the idea of moving one of them next season. Josh has his right to toys and to bring in his own, especially to a 90 man roster. He brought in Lloyd and Salas last year.
I don't see how discussing whether Tebow is ready to compete for a starting job in the NFL is really relevant. The reality is that no team, not one, was willing to give Tebow that opportunity.
My position is clear on the quarterback position. I would rather have kept Hoyer and paid him, rather than give up a 3rd for the second time in the last few years. Personally, I don't know whether signing Tebow is an admittance of failure with Mallett or a hope that we can trade Mallett, or both.
What I DO KNOW is that Tebow has shown me no reason to want to have him on the 53 man roster. I suppose that he could be inactive and carry Brady's clipboard. Actually, I don't recall if an inactive player is allowed on the sidelines.
HOWEVER, in the end, we will carry several developmental players who are likely to be inactive in every game, or at best be active to play special teams. Tebow could be kept as a developmental player. Personally, that wouldn't be my choice.