"The system"?
"Interchangeable Wide Receivers"?
"we Lucked Out"?
Redskins couldn't have won squat without those players, a simple fact you must begin with as the foundation for winning. The coach and his system are entrusted to get the most out of the players, but it was the coaching staff and Joe that brought it together, which you allude to. The system is always going to be changed to suit the skill player, it wasn't a plug and play offense. Its hardly luck.
And besides, the defense was rather very very good.
Gruden's got a system too, but not the horses to make it work. Plugging Robert in, isn't going to work as we have seen. When Gruden makes his adjustments, and tailor his game plan to the strength of his players, then we'll see progress. The premium is on coaching here, not the system.