Marmol wasn't a good starter at all because he doesn't have a good third pitch. That's why he was converted into a reliever. You can be a dominant reliever with two good pitches, as Marmol proves. marmol was a good starter in the minors that time has likely passed, obviously, but the reason marmol wasn't a success as a starter in the majors go way beyond the lack of a third pitch No, not really. He struggled as a starter as a rookie, that doesn't mean he would never have become a good starter. His change is passable, his control/pitch count would have needed work. You may be right (I'd call his change up as mediocre at best, and that's maybe a little generous), but the perception of not having three major league pitches in the front office most certainly was the deciding factor in him converting into a reliever when he went down after those initial struggles. Had he had a better change than what he does, I think his chances of sticking as a starter three years ago would have been considerably higher. His conversion into a reliever was because the Cubs needed an extra bullpen arm in the middle of the year last year, and Marmol was the best choice (at the time he was doing well as a starter at Iowa). So that's why he was the one called up, and he ended up being so dominant as a reliever that the Cubs decided to keep him there rather than risk switching him back. The perception of 2 pitches might have factored into them keeping him as a reliever (although I think his dominance was a much bigger factor), but his conversion into a reliever was strictly need based.