Newly-Extended Perez Must Improve Breaking Stuff to Take Next Step

The Texas Rangers have locked up yet another young left-handed starter, signing Martin Perez to a four-year, $12.5 million extension with three club options that could extend Perez's stay in the Lone Star State to 2020 and pad his pockets to the tune of $32.5 million.

A perennial top prospect, Perez erased memories of his rough big league stint in 2012 by posting a park-and-league-adjusted ERA that was 14 percent above average (114 ERA+). The 22-year-old enjoyed arguably the best rookie season ever for a Texas lefty, as only Mike Mason (114 ERA+ in 1984) matched him while throwing 120+ innings. Perez displayed sharp control (2.7 walks per nine innings) and racked up ground balls (47.9 percent of pitches put in play), both of which bode well for his future. But he also punched out just 6.1 batters per nine frames, far below the 7.2 average for starting pitchers in this strikeout-saturated era. To get more swings and misses, Perez will have to improve his pitch location with his breaking stuff.

Perez already has an out pitch in his changeup, which generated far more whiffs (39.7% of the time batters swing) than the league average (29.4%) and limited hard contact (.307 opponent slugging percentage, 90 points below the MLB average). His curveball and slider, on the other hand, induced swings and misses just 19% of the time (29.9% average for breaking pitches) and were frequently laced into the gaps (.437 slugging percentage, 92 points above the MLB average).

Why did hitters square up Perez's breaking pitches? The young lefty struggled to command his slider and curve, too often leaving breaking balls over the heart of the plate:

Perez's pitch location with his slider and curveball, 2013

Perez threw 29% of his sliders and curves to the vertical middle of the strike zone, third-highest among lefty starting pitchers in 2013. Belt-high breaking stuff tends to get clobbered, with hitters swinging through just 12.9% of sliders and curves thrown over the middle of the plate and slugging a collective .461. Perez was no exception, getting whiffs 13.8% of the time and allowing a .556 slugging percentage when tossing a belt-high breaking pitch.

The recent history of low-strikeout lefties who nonetheless posted quality ERAs during their rookie season is mixed. On the wildly positive side, Andy Pettitte pitched into his forties and cobbled together a career that may get him some Cooperstown consideration. However, the list of low-K lefties (six or fewer strikeouts per nine) with an ERA similiar to Perez (10-20 percent better than the league average) also includes the likes of Gustavo Chacin, John Lannan and John Halama. To be more like Pettitte and less like Halama, Perez needs to complement his knockout changeup with better-located breaking pitches.