Two telling quotes are (IMO):
Chris Boardman: Sutton was “an excellent No 2” but perhaps not the right man to be “the big boss”.
Rob Hayles "He worked extremely well alongside Sir Dave Brailsford. They were good cop, bad cop, but unfortunately bad cop, bad cop does not work at all."
Sutton sounds like he was promoted one level beyond his abilities into a role that did not suit him, by an organisation aware of and not interested in addressing his behavioural problems. Someone a bit smarter at the helm would have realised that to maintain the status quo Brailsford needed to be replaced with a like for like PR friendly, person-management skilled individual, capable of making big decisions, leaving Sutton bullying people and making small decisions in his tracksuit in the background.