Breaking down Felix Doubront's struggles

Through the first three games of the season, Felix Doubront has not been particularly sharp on the mound. The 26-year-old southpaw sports a 6.75 ERA, 1.77 WHIP with eight strikeouts and seven walks in 14.2 innings pitched. Some have begun to doubt the Carabobo, Venezuela native's future in the Red Sox rotation. Statistically, Doubront has been routinely average the last two seasons in the rotation. Last year, Doubront posted a 4.32 ERA with a 1.43 WHIP, 139 strikeouts and a 0.9 WAR in 162.1 innings pitched.

Despite his average overall numbers last year, Doubront displayed a stretch of dominance through three months of last season. From June through August, Doubront posted a 2.96 ERA, .238 BAA, 76 strikeouts, 33 walks while maintaining a slightly above average .283 BABIP in 97.1 innings pitched through 16 starts. Doubront demonstrated an ability to be consistently reliable for at least six innings per outing.

Doubront's performance was significant during those three months. "Rotation ace" Jon Lester posted a 4.35 ERA with a .271 BAA, .311 BABIP, 80 strikeouts, 37 walks in 99.1 innings over 16 starts from June through August. When Lester was inconsistent, Doubront provided an solid, constant lefty presence in the rotation.

But right now, Doubront does resemble that guy that displayed dominance for stretches of last year. Now is a good time to look at the differences between Doubront's performance, tendencies and mechanics last year versus his first three starts this year.

One thing that I noticed immediately during Doubront's first Spring Training start was the tweak in his windup.

One thing that is immediately noticeable in the windup from Spring Training is the reduction of some of superfluous movement in his windup. Doubront moves his glove significant less and the throwing arm motion is significantly reduced. The reduction of extra movement in the windup allows Doubront to have a more mechanically-sound windup that limits potential future arm trouble and allows Doubront to use his legs more towards the plate. The removal of extra movement also resulted in a quicker windup towards the plate.

Since Spring Training, Doubront has seemingly found a middle ground between the two windups.

Doubront reduced the amount of arm action he has, allowing him to use more of his lower body to pitch rather than just his arm. The reduced arm action has removed a lot of extra movement from Doubront's windup that served as an unnecessary extra variable. One thing that has come with Doubront's tweaked windup is a slightly adjusted arm slot.

Doubront in the red jersey is from last year while the Doubront in the white jersey is from his recent start against the Texas Rangers, when he allowed five runs in 2.2 innings pitched. Doubront's release point rose ever so slightly in 2014 from where it was in 2013. Data from Pitch F/X says that Doubront is releasing his pitches at an average vertical height of 6.54 feet. In 2013, Doubront released his pitches at an average of 6.464 feet off the ground.

This new release point from Doubront coincides with a significant drop in movement on his sinker. In 2013, Doubront's sinked moved an average of 8.48 inches while in 2014, his sinker has moved 7.73 inches, a drop of nearly nine percent in movement. The drop in movement suggests why Doubront has shied away from the sinker. After throwing it 14 percent of the time during his June-August stretch last year, Doubront has only thrown his sinker nine percent of the time. While he has used his slider less, Doubront has begun to throw his changeup, curve and cutter more, with rises from 14.26 percent to 16.1 percent, 12.67 percent to 13.98 percent and 12.67 percent to 13.98 percent respectively.

While Doubront has used his change up more this year, the amount of movement on the pitch has decreased as well. After moving 7.55 inches horizontally during June-August, Doubront's change up during his first three starts has moved only 5.92 inches horizontally.

The correlation between Doubront's drop in changeup and sinker movement is not coincidence. When Doubront is able to mix his changeup and sinker in well, Doubront has had success. One key relationship between Doubront's sinker and his change up during June through August of 2013 was the similarity in horizontal release point and movement. During that stretch, Doubront's sinker and change up moved horizantally at 7.57 and 7.55 inches respectively. With both pitches moving a similar amount and being used at the same rate, Doubront was able to deceive hitters by mixing the pitches. Through three starts, the dichotomy between the two pitches is much larger. Doubront's sinker is moving 7.00 inches horizontally while his change up is moving only 5.92 inches horizontally.

Doubront's massive drop in change up movement, decrease in the use of his sinker and increase in disparity between the release points has made his sinker less effective. The sinker has been hit into play at a 31.82 percent clip, up from 19.70 percent from last year. In addition, Doubront's curveball has been hit into play 24.24 percent of time, up from 10.86 percent last year.

Finally, Doubront is just not throwing strikes, and when he is, there are in the wrong places.

Doubront is throwing pitches up in the zone and low out of the strike zone with a higher frequency. In addition, Doubront is not hitting the corners. When Doubront hits the corners and controls the whole strike zone, he has been most successful, as shown in the heat map from his June-August stretch.

Felix Doubront has shown that he can be an extremely good pitcher for an extended period of time, as seen last year from June through August. He has shown that he can be a guy that the Red Sox can count on for at least six inning with only a couple of runs given up. What he hasn't done this season is show any resemblance to the guy who flashed that mid-to-upper rotation potential. Doubront's slight mechanic tweaks have coincided with a drop in movement for his most important non-four-seam fastball pitches: his sinker and his change up.

Until he figures out how to throw strikes consistently on the lower half of the strike zone and rediscovers his feel for his changeup and sinker, Felix Doubront will always be the back-of-the-rotation starter that teases you with great stuff, makes you want more and disappoints you.