Pct = .5 + 1.3246*OPSDIFF
The Red Sox had a team OPS of .792 while allowing their opponents .698, for a differential of .094. The equation estimates they would have a .6245 winning pct. That would be 101 wins. But they actually won 108 games. Maybe it was because they did so well in High Leverage situations.
They had a .854 OPS in High Leverage cases while allowing .649. Using the same years, here is the regression equation when breaking things down by leverage
Pct = .5 + .306*LOW +.420*MED + .564*HIGH
Where LOW, MED and HIGH are the OPS differentials in the three cases. That equation estimates they would have a .666 winning pct., good for 107.9 wins. So it looks like their High Leverage performance added about 7 wins.
In case anyone is curious, in LOW, MED and HIGH case for all of MLB this year, OPS was .724, .734, .724, respectively. So on average, teams do about the same in all cases. But the Red Sox were much different than that.