definitely the latter. the three bowlers (plus prior) were almost untouchable
I think the idea amongst the team was swann/anderson/broad will win matches if the other guys support them. A third seamer to do donkey work, a top 6 to consistently grind out ~600 in a match rather than set 450/500 first up. Explains why finn was marginalised and underutilised as an uneconomical wicket taker (i.e. match winner) and the one batsmen capable of singlehandedly winning matches and the side's actual best player wasn't handled like that type of player should have been.
Everything was geared around them, they knew it and they acted like it.