It is a good thing that the quality of the head coach and the quarterback has such a big effect on the team’s performance from their supporting cast around them. A great coach or QB can bring the play up of those surrounding them, though bad performances from either of those spots can be extremely debilitating as well.
According to Pro Football Focus the Raiders are going to need coach Jon Gruden and QB Derek Carr to be great because they do not currently like the supporting cast around them. The training camp preview series that PFF runs each year is out, and they provide grades of between Tier 1 (highest) to Tier 4 (lowest) for each team’s supporting cast.