Maybe I'm recalling wrong, but wasn't Armstead already the starting LT when Peat was drafted which resulted in Peat trying to be a RT, which he failed at, and then a RG, which he failed at, which resulted in him being moved to LG? I don't think he was ever really given a shot at LT until this past year. When he got his shot, he was an average LT. Clearly we want to upgrade but, if he can play the scheme, he would have been a solid depth piece at this point. But, I do think age has caught up with him and he is not as agile as he once was.
And he was mostly a good LG. The problem was he also got injured a lot. It's not what you really want from a #13 pick, but he was still a good LG for several years although injury prone. It was probably time to move on, but I still worry that we don't have anyone behind Penning at LT (other than seeing if Fuaga can switch sides) and Penning is no sure thing. So, even if he wasn't a scheme fit, I would be more confident about the position if I knew we had an average veteran behind Penning. That doesn't have to be Peat, but unless someone shakes loose before the start of the season, there really aren't any options on the free agent market.