Championships since purchase by John Henry group: Red Sox 4 Yankees 1
The Red Sox are 8-1 in their last 9 postseason games against the Yankees.
As much of a commitment as these massive contracts are, it might be worth noting that only 12 contracts in MLB history have exceeded $200mill, and four of those players (Stanton, ARod, Cano, Prince Fielder) were actually traded during these mega deals.
So historically any team signing Machado or Harper has a 1 in 3 chance of pawning that deal off on someone else at some point...