How good Wilson is does not affect whether Graham was a reach or not. If he pans out as a starter, that makes Wilson a steal for the Seahawks. No one was expecting him to go so high, or to play as well as he's played. You have to look at each player for their own merits in relation to when they were picked. McKelvin is a disappointment for a first rounder, even though it looks like he's found a home as an entirely capable nickel corner.
Now, I was one of the people who was not a fan of the pick, and it's still early but there's no denying that he can stretch the field and is learning his routes at least well enough to pull off that 64 yard grab. He's definitely not completely there yet, but none of our rookies are. I would not be surprised if he makes a play for #2 WR sometime this season.