I'll go one further. The only reason Tebow does not start is because NFL teams would rather fail in a traditional way than try something new and risk criticism. Tebow shows how intellectually bankrupt most bad teams are (I'm not gonna blame a good team for failing to take a shot on something different, but some place like Buffalo or Jacksonville?)
I'm torn between this and my personal thought that he just isn't good enough, but I agree at least with your premis, Tebow aside.
Change seems to be frowned upon. I get why, coaches/GMs in reality, are trying to save their jobs for one more year as opposed to actually trying to build a winning team. Those 2 things are not always exactly the same.