Throughout the Oakland Athletics‘ 11-4 win over the Texas Rangers on Wednesday afternoon, it was clear that Jarrod Parker was in control of the game on the mound. But what the game did not tell the viewer is that Parker is in the midst of an unhittable stretch.
Parker has not lost a game since May 22 in Texas, a stretch of 18 starts that has seen him post a 9-0 record during this time. During this stretch, Parker has lowered his ERA from 5.76 to 3.57 and gone at least six innings in 16 of the 18 starts, a great run for any pitcher.
While these baseline statistics explain that Parker is in the midst of one of the best stretches by any pitcher in MLB this season, it does not explain why the light suddenly switched on.
Upon further analysis, it is clear that this step up in performance has to do directly with Parker’s switch from primarily throwing a four-seam fastball to now primarily throwing a two-seam fastball. During the 2012 season, 42.5 percent of the pitches Parker threw were four-seam fastballs, while 20.5 percent were two-seam fastballs.
In 2013, this ratio has nearly flipped itself, as Parker has thrown 26.7 percent four-seam fastballs and 36.5 percent two-seam fastballs. This switch is important because the two-seam fastball — otherwise known as a sinker — keeps the ball on the ground much more than the four-seam fastball normally does.
At the outset of the season, it was clear that Parker had a tough time adjusting to this new-found approach as he allowed 11 home runs in his first 10 games. Since that dreadful start, he has only allowed eight home runs in 18 games, a drastic improvement.
This adjustment to becoming more comfortable in relying on two-seam fastballs has clearly had a large part in the light switch that was turned on near the end of May for Parker. Since that time, he has been nearly unhittable, and has quietly developed into one of the best pitchers in all of MLB.