Phil Wheeler was an All-American and the GT MLB. They used Guyton as his relief, and he looked good doing that, but he was a reserve. They tried to use him as a OLB and he stunk at that. The combination, not starting in college at ILB, and stinking at OLB, made him an UDFA. After all, if he can't start in the NCAA, how good can he be in the NFL?
Phil Wheeler was and is a good player. He was drafted by Polian in the third round for the Colts, as a MLB. Guyton is better as a ILB, then MLB, but probably as a WILB, more so than a SILB. Once again there is a guy in front of him at his best position. Now its not Wheeler, but DROY Mayo.
I think that Guyton will eventually turn into a red chip player at ILB for the Patriots. He does an adequate job taking on the G and shedding, and has great range, and some coverage ability, but he will never be a Maulauga/TJ run-stuffer. But the Pats still need an ILB that has ILB confined-quarters, pass rushing ability. That ability is different than being able to out quick and turn the corner, pass rushing as an OLB.
Just like Tedy had in his prime, as he was an ultra quick interior DT pass rusher in college. That is a quick shed, or agility to make them miss, and then make yourself narrow, running through an inside gap directly at the QB.
So far that is not a Guyton nor a Mayo demonstrated ability. They need to find it or develop it in Mayo, or draft it, to have a feared pass rush. The rush can't come from the OLBs only.
I would like to point out that Belichick indicated that the Strong Safety position is turning into a coverage tweener from the old run-stuffer, in-the-box, Safety. I think he would say the same would apply to the anachronistic, TJ run-stuffer ILB too. They will be much more as complete ILBs, able to do both run-stuffing and some coverage capability, like Guyton and Mayo.