Despite our continuous managerial calamities, we're still an attractive proposition for any ambitious manager out there.
Re-iterating what Power said, Levy will speak with potential managers and explain our ambitions, resources and how we want a manager who can match and possibly further those, the manager will do their upmost convincing Levy they are the man, get the job but once things go sour it's always the "best we'll get"/"overly ambitious"/"lack of resources" excuses that get thrown about.
Appointing a quality manager that can bring success is extremely hard, if it were easy then all teams would have success. To Levy's credit he's tried almost every type of manager over the years. Santini at the time had just left the France post and so came with a big reputation, he left then Levy gave Jol the job. An unknown entity who was a catalyst in our rise back into a Europe. Jol got sacked and in came the manager who'd just won back to back UEFA Cups, won us our first trophy in years but League form was atrocious. He went and in came Harry, a man known for man management and being a veteran in the Prem, done superb for us and took us into the Champions League. He went then in came AVB, a young manager who had a torrid time with Chelsea but an impressive quadruple with Porto and was dubbed the new Mourinho. Clearly wasn't the new Jose and now we have Tim, again, another young manager but someone with no managerial experience though does have a lot of knowledge of the club having been a player and coach.
It's not as if Danny boy has appointed a similar calibre of manager each and every time, he's mixed it up to unfortunately little success.