How about instilling a resilient "we believe" attitude that is JOB ONE for any head coach. And getting his players to play for each other, through thick and thin, and buy into the shared goals and objectives. These are skills that are very hard to define and find--and the reason so many NFL HC's flame out, IMO.
I'm not putting Marrone anywhere near the same category, but how many people actually thought Parcells called offensive plays or designed schemes for the Giants? Or Mike Tomlin for the Steelers?
It's remarkable (to me anyhow) how many TSW-ers focus on play calling (when in fact for any given snap the QB has several options that are out of the hands of the OC or HC, as do the WRs in terms of their sight reads) and don't see the cultural 'big picture' of what coaches really do--set the tone, put players in position to use their skills, and then trust (hope) that those players execute.
Marrone's far from perfect. But he's the first Bills coach in a long time that has the players 'buying in' and fighting, not folding when it would be easy to do so.