Yes. I suspect that Marmol's leverage will get higher as the season goes deeper, but I won't use that as an argument. If we are getting into the specifics of Marmol rather than the generics of dominant relief pitchers versus dominant starters, then there's a few questions we need to ask ourselves: 1) How likely is Marmol to maintain his performance from last season, or that last season represented a true ability level? Pecota is not kind to Marmol at all, projecting a big regression to the mean. Similarity scores on baseball-reference.com come up with three players that I consider good comps for comparable points in his career: http://www.baseball-reference.com/w/wettejo01.shtml http://www.baseball-reference.com/s/scanlbo01.shtml http://www.baseball-reference.com/p/plunker01.shtml We're not likely to be getting another 300 ERA+ season from Marmol, to be sure, but I think it's reasonable to expect him to continue to be a top-notch reliever. A top-notch reliever with a good but not great leverage index pitching in the 80-90 IP range is generally worth 4-6 wins above replacement (http://www.baseballprospectus.com/statistics/sortable/index.php?cid=208950 for a list of last season's relievers, Marmol was at 3.7 with fewer innings and worse leverage than we can expect), so I think that's a good base projection for Marmol as we have him now. 6.0 wins above replacement last season was Erik Bedard, 5.0 was Carlos Silva, 4.0 was Doug Davis. 2) Would "starter Marmol" be in that range of pitchers? PECOTA is pretty harsh on Marmol, projecting him to about a 3.83 ERA. ZIPS has him at about 3.77. I think both of those are a bit high. Some of those comparable players I think point to an ERA in the high 2s, low 3s. On average, a pitcher gains about .8 runs in ERA when he goes from relieving to starting and loses it when going vice-versa, but that's a very generic number and varies a lot from case to case. But we don't have anything better to go with on Marmol, so I think that's a fair assumption. Depending on whether you are using the statistical projections or the comp projections, that would put Starter Marmol at anywhere from an ERA in the high 3s to the mid 4s. I don't think he'd be an innings-eater, so even our most optimistic projection as a starter puts him as a 190-200 inning, high 3s ERA type of guy. That's a lot closer to Doug Davis than Erik Bedard, using our above baselines. So I think that lays out a good case that moving Marmol from relief ace to starter would be essentially a wash at best. 3) Do the Cubs need to make such a move? The Cubs are really deep in both the rotation and the pen. I'm going to assume he replaces Dempster in the rotation (and not something stupid like replacing Hill), which would make the most sense despite Hendry and Piniella being buddies with him. A pessimistic view of Dempster would be something like what Milwaukee got from Dave Bush in 2008 (186 innings, 5.12 ERA). That was worth 2.2 wins above replacement, so I'd put replacing him with Marmol at about two wins worth of improvement to our starting rotation. We could probably get the same improvement from Marshall, and almost as much from Lieber, but that's a real improvement. If Marmol replaces Marquis, that's a little less improvement. So would taking Marmol out of the pen cost more than the 2 wins we'd gain? I think so. We have a deep pen with good relievers, so everyone right-handed and not a long man behind Wood moves up a notch. Howry replaces Marmol, Wuertz replaces Howry, Gallagher? or someone replaces Wuertz. Hart and Lieber probably stay in their current roles. I'd say that's a net loss at each switch, and it'd only take an average of 2/3rds a win above replacement loss per move to cancel out the gain from Marmol in the rotation. All in all, I don't think the risk of the move is worthwhile for a team that is already playoff-worthy on paper.