And you are one who typically believes "pitching equals parades." I believe that is a direct quote from you. And absolutely has some merit.
As for this year's Red Sox team, I don't think losing Mookie will be what keeps them out of the post-season. Last year, they were a top 3 (runs scored) or top 4 team (fwAR) in offense, depenind on which metric you prefer. In both cases, they were the highest ranked team to not make the post-season.
Pitching was another matter. They were closer to the middle of the pack in just about every metric. Pitching really was why they did not play in October.
Right now, the real big problem is, their pitching is probably worse. Their biggest addition (Perez) has never been as good as their biggest subtraction (Price). The bullpen, maligned as it was, appears to only be adding a rookie who puts the "wild" in "wild card." There was a modest farm upgrade, but so far no one has really been moved to address these areas. The Sox have added a few questionable middle infielders (Pereza, Arauz) to supplement their incumbent questionable middle infielders (Chavis, Lin, Hernandez), and done some bench patchwork. These are nice upgrades, but the team finished 12 games behind the second wild card team. Also, the Bloom has loaded the back end of the 40 man roster with fringy relief pitchers discarded by other teams. Obviously he sees something in a few of them that I don't. But I doubt it's 12 more wins...