On Saturday, I took a look at the biggest underperforming pitchers based on ERA and SIERA differential. Today I look at the opposite, those pitchers who have most outperformed their SIERA and are ripe for a correction. These guys make perfect last minute sell high candidates in your league this year, especially if you are out of it and still have the chance to make dump trades for keepers. Otherwise, this may be your early list of overvalued pitchers in 2012 drafts.

I wrote about Johnny Cueto about a month ago, and he has continued to cruise along, easily leading all pitchers in ERA-SIERA differential. The increased GB% has stuck, as it has been around 50% every month, and 60% in June. His .225 BABIP also leads the league, which is somewhat supported by his 14.9% line drive rate allowed. With only 128.1 innings pitched so far, he may not be that overvalued next year. However, there are so many question marks, like whether he could sustain that increased GB%, and whether his K/9, currently in freefall, could rebound, that it would be extremely risky given that you are already looking at major luck regression to begin with. I will not advocate avoiding him in next year’s draft because I don’t know how much he will cost, but I would bet his ERA looks more like the 3.64 he posted in 2010.

I was a fan of Jeremy Hellickson in the pre-season, and so far on the surface he is proving that I was right to be optimistic. However, his K/9 has dropped sharply, despite a strong 10.1% SwStk%, while his BB/9 is at a level he has never before posted. As an extreme fly ball pitcher, he needs to get those strikeout and walk rates back in order, as the .235 BABIP and 80% LOB% are not going to last forever. Next season, I would bet his skills improve enough so that his ERA does not approach his 2010 SIERA, but I still think it’s headed up into the high 3.00 range.

Ryan Vogelsong has been one of the biggest surprises in baseball this year, and although his peripherals suggest that he has actually pitched pretty well, his xFIP- is right at league average. Of course, this still means that it’s the best Vogelsong has ever pitched. Most fantasy owners will probably be smart enough not to draft him next season, but I could see him going for $5 or so in 12 team mixed leagues. My guess is that 2-3 weeks later, he will be back on free agency for the next brave soul hoping to catch a second strike of lightning.

Jered Weaver is putting together a strong Cy Young campaign, but he may be the most dangerous to fantasy owners on this list. Besides his debut in 2006, he has posted the best BABIP, LOB% and HR/FB ratio of his career, all in this one season. It is nice to see his control take another step forward, but his K/9 has dropped right back to where it had sit prior to last year’s spike. Now it appears that last year was the fluke, and if he cannot muster another 9.0+ K/9, then he will probably be looking at a similar season to 2009, when he posted a 3.75 ERA. His great fortune this year will very likely get him drafted as a top five starter in many leagues, but I think there’s a good chance he ends up finishing the season outside the top 10.

The decline has begun for Jair Jurrjens, as he finally posted ERAs over 3.00 in June and July and has so far allowed 10 runs in just 11 innings in August. His peripherals inspire little excitement, so he is getting by solely by keeping his BABIP and HR/FB ratios well below league average. Are you willing to gamble he is one of the few pitchers who has this amazing talent? Jurrjens’ strikeout and walk rates look similar to Cueto, but at least Johnny has a 50% ground ball rate. Jurrjens somehow managed that mark once in his career, but has sat around 40% every other season. As a Braves fan, I like to see Jurrjens continue to pitch well, but being a realist, I just cannot imagine it continuing at this level for much longer. And without much strikeout potential, his fantasy value simply has much more downside than upside.