Martin Perez's Changeup a Plus Pitch

Martin Perez has stepped forward as a crucial part of the Texas Rangers' starting rotation, providing quality outings with Matt Harrison (back surgery) out for the season. The 22-year-old lefty has done a pretty convincing Harrison impression thus far, making up for a modest strikeout rate (6.2 per nine innings) with few walks (2.6 BB/9) and plenty of ground balls (49 percent of pitches put in play). Perez's park-and-league adjusted ERA is 22 percent above average this season (122 ERA+), besting all American League rookie starters throwing at least 75 frames, save for Tampa Bay's Chris Archer.

Perez is thriving thanks to his changeup, which he has tossed 24 percent of the time. Opponents are slugging a paltry .287 when he pulls the string, putting Perez's change just outside the top 10 among starters and ahead of changeup aficionados like Matt Cain (.291), David Price (.313) and James Shields (.315).

What makes Perez's changeup so nasty? Here's more on Perez's plus pitch as he prepares to take on Chris Sale and the Chicago White Sox.

• Perez buries his changeup at hitters' knees, locating nearly two-thirds (65 percent) of them down in the strike zone. The MLB average, for comparison's sake, is about 56 percent. Keeping his changeup low, Perez has induced a ground ball 60 percent of the time that hitters put the ball in play (51 percent MLB average).

Perez's changeup location

• He's getting hitters to chase his changeup off the plate about 42 percent of the time, compared to the 36 percent MLB average. Batters are a combined 3-for-26 (.115) when they chase Perez's change out of the strike zone.
• The lefty uses his changeup in any situation, throwing the pitch with nearly the same frequency whether he's behind the hitter (22 percent), even (23 percent) or ahead in the count as (27 percent).
• Perez's changeup is unusually hard, with an average velocity (84.7 MPH) well above the league average for lefties (81.9 MPH). The only southpaws who throw a speedier changeup are Francisco Liriano (86.3 MPH average), Jon Lester and Jose Quintana (85.3 MPH).