Originally Posted by Kc61
I don't agree with the way you framed the question. A starting pitcher may be more valuable than a reliever typically. But Chapman wasn't just a reliever. I think you have to weigh his value as a starter against his value as a top closer.
And while, as Doug often points out, a single reliever isn't that critical, I think differently about premium late inning relievers. Guys who regularly cover the 8th or 9th inning effectively. Not the same thing as a middle man innings eater.
The problem here, of course, is that Chapman's success level as a starter is unknown. So it's trading a relatively sure thing in the bullpen to something more questionable in the rotation.
To me, this one is for the professionals. They have to project how good a starter Chappy can be. If they believe he has enough different pitches, stamina, etc., and is likely to be a first rate starter, the decision is made.
If they think the odds of him being a first rate starter is in the 50-50 range, I think he stays in the pen.
The difference between the best closers and the bottom half in the game over a long enough timeline is only about 10% in save percentage (low 90's to low 80's save percentage). Most closers will get about 40 to 50 chances to close. So 4 to 5 games difference, but not all blown saves turn into losses. 1 out of every 3 blown saves turns into a win. So you are looking at 3 game difference between a below average closer and one of the best in the game. If Chapman is only an average starter, I am willing to bet he could easily turn around 3 games started by Leake, and if he is a top 25th percentile starter there is no doubt he would make that up with ease.