As long as there is any sort of market in the game, it is inevitable that the success of teams will depend on how they manage their finances. This is directly proportional to the amount of teams in the game, and the 'age' of teams -- and is not necessarily conditional on game changes such as the staff.
I am yet to see how this issue can be eliminated without turning it into a clone of
(http://www.mobygames.com/game/lakers-vs-celtics-and-the-n...).
"I don't know half of you half as well as I should like; and I like less than half of you half as well as you deserve."