I don't agree w/ the holes you poked....
Bills business changes can be reflected as readily as can those instituted by a private sector CEO given the context of their respective environments. Frankly, much of the revenue the Bills receive isn't even dependent on on-field success, e.g., TV revenues that are portioned out just for existing.
One can make the argument that injuries to key players have little or no impact on the bottom line, and certainly there is ample evidence that poor performance is almost a keystone of the Bills "success" in that failure appears to breed continuing season ticket sales, often at increased prices.
GM certainly does face obstacles wherein their assets don't operate: See this week's newspapers.
i believe the Bills is a business all too much like any other private sector business in many ways; where they differ is that the Bills can "sell" (not offer, sell) an inferior product over long periods of time and not fear losing their customer base. Tragic, but true.
So, again, I believe it is totally fair to judge Mr. Brandon from both the business and the "sports" perspectives: Successful in the former; unsuccessful in the latter.