Well, as we all now know, the team was historically dominant this year, setting the franchise record for wins in a season at 102. But, the team didn't have its four aces for a good portion of the year. Could the Phils have won even more game if it had?
Comparing the games with and without the four aces intact indicates probably not. In fact, the team saw better starting pitching and better outcomes when the four aces were not intact.
The Phillies had an intact four-ace rotation for 108 games, exactly 2/3 of its games. In these 108 games, all four of the pre-season aces were healthy and starting. (This number isn't easily divisible by 5 because of double-headers.) In 54 games, or 1/3 of the season, the team did not have the four ace rotation intact. For much of this time, Roy Oswalt was injured, but Cole Hamels also spent some time on the DL.
Here's a basic comparison of these two periods for the team's winning percentage and cumulative starting pitching stats:
As this chart shows, the Phillies won at a better clip with only three aces, rather than four. They also had better overall starting pitching during that period. Of course, with the four aces, the team still excelled and the starting pitching was still incredible. But, thanks to Vance Worley and Kyle Kendrick, the team didn't miss Roy Oswalt or Cole Hamels when they were gone. In fact, the team did even better without them.
This isn't to say that the Phils shouldn't start the four aces in the playoffs. Rather, this exercise merely shows that the team did not suffer because of the extended absence of the pre-season advertised rotation of four aces. And, this also shows that Vance Worley and Kyle Kendrick really performed beyond our wildest expectations this season.