For some reason I started a spreadsheet on this last July so I just went back and updated the 2011 wins/losses. In the Gardenhire era, the Twins are 38-33 against the Orioles, 30-32 against the Red Sox, 18-51 against the Yankees, 42-30 against Tampa Bay and 29-41 against the Blue Jays. 157-175 against the A.L. East overall. (Totals came from baseballreference). (I think these are only regular season games).
As I look at it now, one of the things that strikes me as a discrepancy is that the Twins have played the Red Sox far fewer times than the other teams (62 vs. 69-71 for the others).
I just now split the totals into 2 5-year segments (2002-2006) and (2007-2011). Their winning % against Baltimore improved slightly from the 1st 5 years to the second (19-18 improved to 19-11). Their winning % against Boston took a nosedive (18-12 down to 12-20). The Twins were 8-23 against the Yankees in the earlier period and then 10-28 in the later period. Their record against the Rays also took a nosedive in the more recent period (27-8 down to 15-22). And again took a nose dive against Toronto (19-13 down to 10-28).
Their winning % against the East was 53% in the first 5 years and 41% in the latter 5 years.
I'm not sure what to conclude from this (and would like to take a look at how some of the other Central teams fared). Overall, has the Eastern Division just gotten that much stronger while the Twins (and the Central in general I would guess) have stagnated? Can all of this be attributed to a lack of power pitching? (I doubt it).
One conclusion I can draw is that while their record against the Yankees has been pretty abysmal over the entire 10 years, their "winning percentage" against them hasn't changed much. But the Twins' performance against Boston, Tampa and Toronto is taking a very unwelcome slide into Yankee territory.