The defense behind him, more than anything else. He's only allowed something like 33 hits in 57.1 IP. Yeah, his K rate, BB rate, and HR rate (and HR/FB) are all pretty comparable to his prior Cubs experience. Its just that coming into todays game he has a 203 BABIP, resulting in a 173 average against. Granted he has only allowed a 14.6 LD%, but thats not really a skill and will regerss to the mean. Regardless of what his ERA says, his underlying statistics show that he was and is a league average pitcher. There's still some interesting digressions from his previous Cubs career that shouldn't be dismissed out of hand. 1) There is a noticeable difference in his pitch selection. He's throwing more fastballs at the expense of sliders. 2) All three of his pitches are coming in at a consistent 2 MPH below when he was a closer, possibly indicating a change in the way he's pitching. 3) Not only is his LD% lower, his FB% is as well, with the difference all going to his GB%. If he was just getting LD-lucky, I wouldn't imagine the difference would be that pronounced. http://www.fangraphs.com/statss.aspx?playerid=517&position=P He's nowhere near as good as his ERA, and I don't know if any of this will be meaningful long-term, but it's curious to say the least. RE #1 I'm guessing this has to do with him having to "conserve" his slider. When you are facing batters multiple times as a starter vs once as a reliever, you have to not show all of your pitches the first time around. I'm guessing this is just correlational with moving to the starting role, rather than a causation for his success. If anything, you would assume that a pitcher who does a worse job at randomizing his pitch selection will get hit harder. RE #2 I'm guessing the reduction in speed can be attributed to the fact that he was only pitching one inning at a time before and could go all out and is now pitching multiple innings and needs to conserve himself and/or get tired later into games resulting in a slower average than when he was closing. RE #3 Yes, his GB% has increased, and hes eclipsed the point where GB% becomes moreso due to skill than luck (ie r^2 exceed 0.5) of 150 batters faced. Thats great an all, but on the flip side that further exposes the luck in his BABIP. Fly balls get converted into outs more than any other type of batted ball, and even though he has a really low BABIP, he has a low FB%, meaning that his BABIP should actually be higher than our standard LD%+.120 estimation (because those non-line drives are mostly ground balls (infact 2:1 in comparison with FB), which are turned into hits much more often than FBs). Well Kyle you must have missed my original response to your comment on Demps peripherals and recreated the wheel is a more indepth manner. One booboo you made in your long post is that you said his increased GB/FB rates are helping his BABIP. Thats not true. FBs are turned into outs more often than GB, so an increase in GBs and a decrease in FB means that a pitchers BABIP should be worse. In Demps case, this isn't happening. When you are talking about a pitcher that has had a change in GB/FB the LD%+.120 estimation for eBABIP simply won't do. I aggregated and weighted Demps ball in play types to come up with what hes done as a reliever for the cubs... LD%=19.9%, GB%=51.3%, FB%=28.8%. There are about a bagillion different more indepth eBABIP calc, but I just pulled the first one I found that was simple. .763*LD+.265*GB+.131*FB. Using this, Demps eBABIP over his previous tenure as a cub was .325, his actual (again weighted) was .301. So lets be generous and say that maybe that formual doesnt work well for Demp or he has some ability to do better than his eBABIP, or whatever (point is I'm being generous here). Lets use that same formula on his batted ball type this year...it yields an eBABIP of .314. My generosity comes in where I adjust that by taking out .024 to say, well luck independet, Demp should have a .290 BABIP this year. When infact he has a .220. My point in all this rambling and my previous post is to consider that Dempster "has fundamentally changed as a pitcher" and that has caused him this success as a miniscule reason (if any) for his success in comparison to his luck. As Kyle more appropriately stated in his last post, if Dempster has fundamentally changed at all, its been ever so slight in comparison to the affect luck has had in the difference between his expected results and actual results.