What Got Into Jason Hammel Last Year?

Jason Hammel was never a big name around the league in his career. A 10th round pick by Tampa Bay in 2002, he just broke into Baseball America's Top 100 Prospect List in 2006. His peripherals were decent, but not jaw-dropping. After not showing any signs of sustainable success in Tampa, things started to click in Colorado, though high BABIPs hurt his results. After a Tampa-like season in 2011, he was traded to Baltimore for Jeremy Guthrie and suddenly Hammel turned into a new pitcher.

First, he started striking out hitters at a good rate, 22.9% to be exact. His other improvement came through his batted ball profile, inducing over 53% groundballs, over five percentage points higher than any other season. Seeing big jumps in K's and GB's while maintaining your walk rate is a near-automatic sign of improvement. How did Hammel create these great results?

Looking at his whiffs, both his in-zone and out-of-zone contact rates plummeted. His curveball and slider each missed the bat around 40% of swings, great numbers for each. Even more surprising is his ability to get a high amount of misses with his fastball. His two-seamer, possibly the most contact-oriented pitch across the league, got 15% misses and his four-seamer at 20%. Averaging 93.5 on both fastballs helps some, but it's still very impressive to see such high whiff rates on fastballs.

His two-seamer, on its own, is very unimpressive, 7.6 inches of tail and 8.1 inches of rise. However, his four-seamer was able to gain some extra life, 9.9 inches of rise, after sitting around 7.5 inches in previous seasons. That extra 2.5 inches is the thickness of the barrel, the difference between squaring the ball up and missing it completely. It's hard to get the barrel on 93-94 above the belt when there is double-digit rise on a pitch.

His change in batted ball profile, especially the GB%, seems to be less sustainable. Using my velocity/movement model, Hammel got over 6% more groundballs than expected. This is especially evident when looking at his four-seamer, as it got 47% groundballs. His sinker got 59% worm-burners despite the lack of true sink. The velocity does help the cause, but expect to see a few more flyballs this season.

His line drive rate and BABIP also dropped last year, though moving out of Colorado helped the latter. A theory of mine, something that may be able to tested by someone with more programming skills than me, is that a "flat" fastball, a four-seamer with less than 8 inches of rise, is hit harder and more often. Hammel did not allow a single home run and only 15% line drives on his four-seamer, opposed to 9 or more homers and over 20% line drives the past three years. One example is not proof, but it shows my theory in action.

Hammel gets the Opening Day nod in Baltimore on Monday, a well-deserved designation. His K and GB rates are likely to regress some, though still staying above average. The Orioles starting staff is not exactly booming in talent, so the veteran pitchers like Hammel must perform up to their expectations to make another run to the playoffs.