Your premise is a little wrong. Slowey was legendary in the minors before his first call-up. He had 4 years in a starter's role with the Twins. He had numerous spats with the front office. If the Twins did not like him, they had a great opportunity to trade him when his stock was high. Instead they killed his career and this event helped set it up that no pitcher wanted to come to Minnesota. Sure, it was a mistake. Trevor May's minor league career does not hold a candle to Slowey's. His numbers as a starter with the Twins are nowhere close to Slowey's. I read several scouting reports on May when the Twins acquired him and many had him pegged as a reliever or a marginal end of the rotation starter. Twins fans were drinking the Terry Ryan kool-aid back then and I think many of us still think May is someone he isn't. I think a better example for the Twins continued mishandling of pitching was the fact that they once had Glen Perkins as a starter, in spite of him having only two pitches. To their credit they did not give up on him and found him the right role. Fast forward to 2015/2016 and you have Tyler Duffey, another 2-pitch pitcher struggling in a starting role. Duffey could be an elite set-up man or a good closer and the Twins are wasting his talents as a starter, just like what they did with Perkins.