Percy Harvin. Even without the injuries and locker room issues, he was a very limited player that had to have touches manufactured for him. Explosive, but didn't run the whole route tree and was anything but a complete WR. A gadget player who's presence on the field often tipped the play call. Dangerous with ball in his hands, sure, but wasn't offering you the complete WR game as similarly explosive WRs with comparatively big names.
Russell Wilson. Maybe we were a little too close to it, but I feel that for a while as Seahawks fans we considered him to be amongst the best of the best and in that top tier of QBs. When in actuality he wasn't a 1st Team All-Pro or MVP type of player, and there was always a pretty clear line of demarcation between him and the truly elite - Manning, Rodgers, Brady, Mahomes. We pumped his tires because he was the Hawks QB, but taking a step away from it, aside from some elite stretches he was usually more of a sub-elite calibre QB - Pro Bowl, not All Pro.