Winston Smith and DPJ:
There is an enormous difference between the time periods quoted. That difference is: team members. I would argue that dismissing the first several weeks of the season is absolutely warranted, simply because the Twins had a totally different lineup. Plouffe wasn't playing, Dozier wasn't up, Valencia was still whiffing at the major league level, Sean Burroughs was on the roster, Jason Marquis was putting up an 8 ERA, Pavano was still pitching, etc. Beginning in mid- to late-May, the Twins were a different team, and that's why quoting the record since then is not cherry picking.
On the other hand, your quoting the record over the last five years is entirely moot, because the teams are all so different among those five years. Hell, even over the last two years, look at the differences!
Between 2010 and 2012, here are the changes. First base is the same, but second, third, and short are all different. Center field is the same, but left and right are both different. Catcher is technically the same, but now Mauer is half-time. DH is different. 3 out of the 5 starting pitchers are gone. The reliever corps is quite different too, but that's expected, so we'll leave them out of the total count.
That means that, total, the 2010 team and 2012 team have about 5 and a half players in common, out of a possible 14. Adding up the stats for the last five years means adding up stats for teams that are radically different. That's why your point doesn't hold.