So how does one break down a Premier League manager's performance?
1) Player Buying - Getting the right players, this is obviously limited by the owner's purse strings
2) Player Selling - Getting rid of aging and un-cooperative and just misfit players is important too, but this is more difficult than it sounds and some managers just hang on to favored players too long
3) Player Development - Obviously this applies to managing young players, but older players also need to evolve their game as their abilities change over time.
4) Squad Management - Rotation: Every manager with common sense does it, but how prepared are the less-regular players to step into a starting role? But if the squad is thin, not much you can do... Managing the squad between the League, Cups, Europe is a huge challenge.
5) Man Management - Motivating players to perform well. Can the manager bring back players whom he's disciplined or had personality conflicts with?
6) Tactics and Opposition Analysis - Fortune favors the prepared, but surprising your opponent that day can work too.
7) On-field Adjustments and Substitutions - In game management can nick a few points here and there
Public Relations - Roy Hodgson at the low end of the scale. Rafa/Fergie/Mourinho at the top end.
Factors outside of a manager's control will affect their performance: Ownership sanity or stability, player budget, squad inherited, personal health (see Houllier), key player injuries, added European competitions, international call ups
