Funny reminds me of @Super Nomario
and a conversation we had last night. Hope you don't mind me sharing here but Bill is the antithesis of arrogance. He believes in constantly innovating, going against the grain, trading down, finding inefficiencies, and not standing pat on his preferred scheme or trading up because he knows best about which prospect (Bill trades up but trades down more). He would delegate authority to coaches and take input from his staff on gameplans. He believes in being going against the herd but if he were arrogant he would think - well I can use the system de jour and just run it better than everyone else even though I am picking 32nd in line and we're fighting over the same players. He used a 3-4 because he could get pick of the litter on nose tackles for example. He rarely if ever trades up in the first round which, again, to me is a sign of not being arrogant. He made a mistake trusting two former head coaches with transferable skills. He made a mistake drafting Ron Brace "I fucked up on that one". He trusts people he is comfortable with like say believing in his friend when drafting N'Keal Harry. If you fail because you believed in someone you trusted that's not arrogance.
It could be taken in many ways man, many ways. The most likely is just that he trusted that two former head coaches would have enough transferable skills to run the offense and/or he might have been trying to get BOB and when that fell through he was left in a spot where he didn't have much else of a choice to do anything but trust his friends could get through it. He fucked up. He fucked up so much he immediately changed things after the season. Arrogant people tend not to admit their mistakes or double down on them.
I think the simplest explanation is just that he was in a rough spot with not a lot of qualified guys he liked available and he made a mistake in trusting Matty P and Joe Judge. That's not arrogance. And given what we know about his other decision making processes it's hard for me to think that's the default answer.