Ummmmm, when we are debating a move that requires us to extrapolate future performance it certainly does. Past performance is never an indicator of future performance. The only reasonable way to extrapolate future performance of pitching is by expecting a regression to the mean that is determined by the process of making outs. ERA, while a great marker for past outcomes, tells us nothing about the process of making outs, thus has ZERO relavence when trying determine future performance. Just because everybody is entitled to their own opinion, it does not mean every opinion is logically sound. Nor does the previous zeitgeist around baseball for the past century, valuing things like seniority and past outcomes mean that what the Twins have done is correct or the opinions of those supporting the move of May to the bullpen are correct.