I don't know either but Kliff did recruit Terrance Steele at TT (started as a RS freshman LT and RT). He is 6-6/310 but doesn't move nearly as well as Becton.
There just aren't many guys Becton's size.
Imagine Becton at LT and Cordy Glenn (your trade option) at RT next year. Both guys for less than what we would be paying Humphries.
Kliff had to take who he could get at TT. He didn't have the luxury of recruiting players who were exact fits.
I know Becton is good for his size, I've seen him play basketball. I would still draft him, I'm just wondering if the Cardinals would see him as a fit.

