Kevin Gregg Re-emerges in Chicago

Over the past few days, many saber-slanted websites (this one included) have devoted articles to the success of pitchers that weren't necessarily expected to see such good fortunes this season. Two days ago, Blake Murphy profiled Pirates' starter A.J. Burnett, and yesterday we were treated to columns on Pittsburgh closer Jason Grilli, Indians' lefty Scott Kazmir, and Diamondbacks closer Heath Bell. Being an aficionado of pitchers with great stories, I have loved the onslaught of quality content. Still, while I agree that quartet of hurlers are all relative surprises; none of them strike me as the most shocking success story of the young season.

No, that distinction belongs to Cubs' closer Kevin Gregg.

That's because as of May 16, Kevin Gregg has thrown ten innings without allowing an earned run. Over those 10 frames, he has faced 39 batters surrendering just five hits and four walks and striking out 12 batters. Because it's just 10 innings, I'm probably making too big a deal out of his success, but remember this is the same pitcher that:

• Was released by the Dodgers during Spring Training. The Dodgers' pen ranks 25th in the Majors in ERA.
• Registered a 4.62 ERA, 4.95 FIP, 4.83 xFIP over the last two seasons. He racked up -0.5 fWAR, -0.1 rWAR, and -0.5 WARP over the same time frame.
• Earned the nickname "Captain Chaos" for his propensity to turn save opportunities into breathtaking ordeals for his coaches and fans.

Yet despite the shaky recent track record, he has been a revelation for the Cubs stepping in as Chicago's closer after both Carlos Marmol and Kyuji Fujikawa faltered. His 30.8% strikeout rate would be a career high by more than 6% and it represents a 12% jump from last season. At the same time, his 10.3% walk rate is right in line with his career mark. As I've noted in my last few pieces, we are nearing the point in the season where we can really trust that those numbers have been real to this point. But that still leaves the big question, can he continue this performance?

Mining through some PITCHf/x data for Gregg, the first thing that stands out has been his pitch selection so far this year. Over the past two years he threw a cut fastball right around 25% of the time, but this year he has scrapped the pitch in favor of a sinker, which he is throwing over 30% of the time. He also is leaning more on a split fingered fastball with more vertical movement than in years past. You can see his pitch mix here:

The new and improved arsenal, plus the uptick in strikeouts make me cautiously optimistic that Gregg can continue his success. Maintaining the strikeout rate will really be the true test. Recently Blake Murphy looked at the factors that predict strikeout rate, and encouragingly Gregg's SwSt% is up significantly from last year. And if his sinker keeps sinking, he may be able to keep the ball in the ballpark better than previous seasons as well. Just a year ago, Fernando Rodney broke the single season ERA record, and now Kevin Gregg may be on his way to a career year at age-34. Man, I love baseball.

Andrew Ball is a writer for Beyond the Box Score, Fake Teams, and Fantasy Ninjas.

You can follow him on twitter @Andrew_Ball.