I don't think that's what he's saying.
You've got several positions - on both offense and defense - which disproportionately affect the game and which, consequently, cost more and are harder to find. Those positions (in today's passing-based NFL) are QB, LT, WR on offense, and DE (EDGE) and CB on defense. The Bills could definitely import a Diggs-like factor on defense in the form of a pass rush specialist. If they added Von Miller to this defense he'd have a similar impact that adding Diggs had to the offense last year, for example.