Yeah, you can get good guards in some later rounds. Second isn't great guard value, especially for a converted center.
For instance,
Guards that would probably have been better?
Other than Manuwai, Taylor Whitley went in the 3rd, a decent road grater type without tons of athleticism but with ability to pull and block inline as well; MOntrae Holland was a bit of a boom or bust guy, but more talented than most guards taken; Ben Sobieski, who's no less of a guard than his teammate Nelson IMO; Tackle/guard types for depth? Steve Scuillo, the massive guy from Auburn; Scott Tercero, Cal;Brett WIlliams, Tony Pashos were both extremely strong; Jeremy Bridges, Makoa Freitas. All guys I think could do as well as Nelson right now.
But then again, backup center wouldn't be filled, and you know you always want to think backup center when you're starting a guard.
Seidman looked allright in preseason. Right now he's probably our best receiver at the position. Mangum has done OK, I guess. Wiggins is mistake-prone but used to be a decent receiver. I expect Seidman to come out smoking next year, though.