Having a successful, long serving manager is an abberation these days. You'll find far more clubs having been successful while going through several managers in the process. It's not about finding that one guy and sticking with him for a decade, it's about cutting short any slumps and avoiding numerous squad re-builds and transitional seasons.
Every manager will have periods when things aren't going well. It is very likely that we will regress to mean in time, but can it happen sooner if we change the manager? Wenger would most likely have been sacked at most other clubs. Even if they're doing well now, was it really worth all the trophyless years? Could a change have improved them sooner?
The quality of the playing squad is far more important. The benefit of a DoF structure and a more long term approach to transfers is getting better value for our money. We no longer have to sell off a large portion of our squad at a massive loss simply because the new guy doesn't like them. Nor are we likely to be saddled with a lot of high earners in their 30s.
Levy has learned his lessons the hard way with players like Bentley.
