First, Mitchell is not on the Red Sox board of directors. He is a consultant to the owners who has no voting rights, or any other rights pertaining to the organization or its operations. If you go through the names, you'll find more Mets listed than any other.
Second, the primary individual to roll over on players is from New York, so it's only logical that those players will show up more often. Also, Clemens, Pettitte and Knoblauch show up because a personal trainer for them was tied to Radomski, who was the primary supplier for the New York area.
Third, If anyone would take the time to read the report (and a few on here have), if there was one individual who comes across as a common tie to just about everyone listed, it's David Segui. Kind of like the six degrees of Kevin Bacon, you know. Much of the report can be traced back to his early involvement.