The Cowboys picked him up as a developmental prospect, and it was obvious as I argued then that they were going to beef him up to play OT. I believe he was signed off of the Saints practice squad, and in doing such he had to be signed to the Cowboys 53-man roster.
Either way, you didn't see Parnell playing as a "blocking TE" as you supposed either, so what is your point, lol?
I think I might try to email one of the local reporters in Dallas to get the real scoop on Brewster. Cowboys' personel won't say openly what the problem with him was, but they usually divulge some info to reporters.
FWIW, I think Tim MacMahon said Brewster just wasn't good, and had a poor football body.