Run Differentials show Sox's superiority
And come to think of it, perhaps it didn't prove even that; the Yankees outscored the Red Sox in the series, 45-41 (yes, that advantage is helped by the Game 3 blowout, but then it's not as though the Red Sox pitchers weren't trying their best). The Red Sox and Yankees played 19 games during the regular season, and the Red Sox won 11 of them.
These numbers are simple
and they're stark. The Yankees outscored their opponents by 89 runs, and the Red Sox outscored their opponents by 180 runs. Basically, the Red Sox were the Cardinals and the Yankees were the Astros.
So how did the Yankees win 101 games, and the Red Sox "only" 98? Essentially, it's this simple: The Yankees were exceptionally efficient, and the Red Sox were nearly as inefficient.