In that scenario (37 to 28) the value they'd be getting for Johnson is really equal to a late 3rd round pick. I wouldn't do it. The only advantage of moving up is the 5th year option thing.
But in a really deep draft where they're not looking at a QB or RB high they're far better off staying where they are and finding a top 25 talent at 37.
I would rather see them use one of their 5th-7ths to move up in the 3rd or 4th.