With the recent trend of 5 inning starters, having a 4 man rotation makes sense. - Using only your best starters will give the Twins more quality innings at the start of games. - Pitching only 5 or 6 innings, on average, would not put undo stress on their arms. - The current trend of 100 pitch counts for starters also helps to limit arm stress (& innings). - The 3rd time through the order usually occurs in the 5th innings, in a well pitched start, it only makes sense to prepare to remove the starter when he starts getting hit. - If a starter is pitching well, they do not have to be removed until they are getting hits or he reaches his pitch limit. - Each starter could have a backup reliever capable of pitching another 2 or 3 innings, which would leave 4 pitchers ready to close out the game. - The backup relievers would be relieving once every 4 days and could easily show which pitchers deserve to be starters. They could easily pitch 100+ innings in a season. - Each starter would start about 40 in a season, and if they average 5 innings per start they would accumulate 200 innings. Imagine if the starters pitch 800 innings, that would leave only 650 innings available to be pitched by the 12 relievers. - 4 starters means 1 more reliever, this would make it easier to only carry 12 relievers and gives the lineup an extra hitter/position player. I love the idea of only using the four best starters in a 4 man rotation.