Prospect Mechanics: NL West

Baseball Prospectus's mechanical mavens Doug Thorburn and Ryan Parker turn to the NL West as they continue their examination of select Top 10 prospects featured in the BP Top 10s (also see their breakdown of AL East, NL East, and NL Central).

Braden Shipley, RHP, Arizona Diamondbacks

Rankings Summary (Diamondbacks Top 10):
Current Organizational Rank: 2^nd
Overall Future Potential: High 6; no. 2/3 starter
Realistic Role: High 5; no 3/4 starter

Armed with a three-pitch mix of potential plus offerings, including a changeup that proves deadly when he pulls the string, the 2013 first-rounder is racing to the big leagues and could be well-positioned to make an impact at the highest level. He was able to cross “hit first professional homer” off of his developmental to-do list last season, but there are still a few items to be addressed before he will be ready to take the leap.

Report Card

Most pitchers have some mechanical disparities between windup and stretch, but the changes in Shipley's delivery necessitate a separate report card. He takes a page out of the conventional playbook with a slide step when pitching from the stretch, and though his strategy is functional in the sense that he spends less time to deliver the baseball, he also breaks the norm with a diminished burst of momentum during his abbreviated stride phase. His windup features two gears of increasing momentum, flashing a 60-grade burst to the plate at peak, but Shipley slows down his forward progress when in the stretch and keeps his weight back. The net result is a shallower release point that was enough to wedge a full-grade separation on his overall scores.

Windup

Stretch

The right-hander also takes a balance hit when pitching from the stretch, with an exaggerated rock-n-roll that is magnified when compared to the low-volume rock that he weaves into the windup. Most of the head displacement takes place in the Z-plane, as Shipley rocks back toward second base before he rolls forward into release point. His timing was inconsistent from the stretch last season, fueling an OPS split of 225 points when compared to bases empty, as the quick timing pattern and relative imbalance wreaked havoc on his ability to find a consistent release point.

His maximum torque reaches the same 65-grade when pitching from the windup or the stretch, but his frequency of achieving that max torque is lessened in the stretch position, where it is more common to see 60-grade separation. His torque features a generous upper-body load and a solid delay to let the hips rotate when the delivery is well-timed, but his trigger was inconsistent last season, with frequent bouts of premature rotation (front shoulder flying open) and excessive delay that left him vulnerable to elbow drag.

Shipley carries a high arm slot that reaches past 11 o'clock from the hitter's point-of-view. The slot results from a combination of average spine-tilt and a high angle of shoulder abduction, and the resulting trajectory makes it easier for the right-hander to hit targets within the strike zone. Many pitchers are restricted to a diagonal of easy-to-reach locations, extending from high arm-side to low glove-side, such that they struggle to hit the opposite corners of the zone; Shipley has the distinct ability to hit targets in any sector of the strike zone, a factor that could maximize his fastball effectiveness as he refines command.

Jonathan Gray, RHP, Colorado Rockies

Rankings Summary (Rockies Top 10):
Current Organizational Rank: 1^st
Overall Future Potential: 7; no. 2 starter
Realistic Role: 6; no. 3 starter

Gray had an impressive debut in the Colorado system after the Rockies made him the number-two overall pick in the 2013 draft, and his rapid development created a buzz surrounding his first full season of pro ball. It can take time for a pitcher to rediscover his groove after the offseason, and he started the year a bit behind in terms of mechanics and stuff, but the right-hander was able to make in-season adjustments to address the weak links in his repertoire as well as his kinetic chain.

Report Card

Gray has an efficient delivery, with a cohesive blend of power and stability that earns him plus marks in each of the four baseline categories. His balance remains laterally solid throughout the motion, culminating in stable posture that flashes a 65 at present and has an 80 ceiling if he continues to hone. The posture is an indicator for when Gray is “overthrowing,” in the sense that his spine-tilt goes south when he goes overboard on the intensity. There is a quick drop in his delivery, though not egregious, with a slight back-side collapse that dings his vertical and Z-plane balance with a single move, though it stands as the only foundational blemish in an otherwise harmonic motion.

He has the big torque to back up his impressive radar-gun readings, and the momentum is very strong from the windup, as Gray leads with the hip and accelerates throughout the stride phase. That flow of kinetic energy continues unabated into release point when he gets some flex in the front knee, but Gray has a distinct tendency to lock out that knee with a stiff front leg as he approaches release point. The stiff front leg is not a major red flag in itself, although it does prevent a pitcher from tracking toward the plate after foot strike and thus shrinks his potential release distance, but the knee-lock impacts Gray as it halts his forward momentum and complicates his transfer of kinetic energy.

The stiff front leg was part of Gray's motion in college, an aspect that was addressed during his cameo of 2013 and which continued to be a focal point of his development for 2014. His ability to find a consistent release point is enhanced by the extra flex in the front knee, acting as a shock absorber from foot strike through release point as he triggers the intense phases of rotation. That energy transfer is critical for Gray as he masters his repetition, and though in-season adjustments and in-game inconsistency harmed his grade in that category for 2014, he sticks to his mechanical framework from the stretch and has the baselines to support future improvement.

Gray is a quick study whose rapidly developing changeup and ability to make mechanical adjustments have further accelerated his fast track to the majors. He is an advanced pitcher whose stats should be taken with huge grains of salt given his developmental agenda, which included sacrificing some velocity in the name of arm-side movement with the fastball as part of the right-hander's quest for weak contact, an element which will be critical when he is playing his home games in Denver. There is a bit of projection built into Gray's B+ grade for his mechanics, but he also has A-level upside if he continues his steep climb up the learning curve.

Adalberto Mejia, LHP, San Francisco Giants

Rankings Summary (Giants Top 10):
Current Organizational Rank: 1^st
Overall Future Potential: 6; no. 3 starter
Realistic Role: 5; no. 4 starter

Mejia's development is on an accelerated timetable. He started the 2014 season as the youngest player in the Eastern League, and though his run-prevention in Richmond paints a picture of struggle, the southpaw's control numbers remained intact while his stuff provided optimism of future strikeouts. His 2015 campaign will get off to a late start, however, due to a 50-game suspension for a banned substance that was announced in November.

Report Card

There are a couple of walking contradictions in the pitching profile of Mejia. For starters, he has a low, sweeping arm slot that leads to lateral volatility in terms of pitch location; combined with his subpar balance, the southpaw has multiple ingredients for a high walk rate, yet he has thus far defied the laws of tradition to limit the free pass as a pro. His vertical balance is strong, but his head drifts around his center-of-mass during the lift-and-stride phases of his delivery, hunching over toward the first-base side before drifting back toward the hot corner.

A pitcher with erratic balance typically suffers the consequence of extra spine-tilt and a shaky release point, but the surprising Mejia overcomes his instability and finishes with excellent posture. The upright spine fuels a low arm slot, and the rotational aspects of his delivery follow a side-to-side pattern, spinning like a top to send Mejia twirling off the mound to the glove-side after release point. He utilizes a heavy load with the upper half to create separation, but his maximum torque is limited by a minimal delay between foot strike and his trigger of trunk rotation, resulting in an average score for torque efficiency.

It's frustrating to watch a lefty invoke a slide step, and Mejia further complicates his approach by mixing it up between a slide step and a half-lift delivery when pitching from the stretch, giving him three distinct timing patterns to master. His release distance also takes a hit with the shorter stride, which could become a bigger problem as he climbs the minor-league ladder. The southpaw does repeat his delivery well in spite of these obstacles, and though his repetition isn't quite as good as his walk rate suggests, his consistency is much better than one would predict given the mechanical underpinnings.

Hunter Renfroe, OF, San Diego Padres

Rankings Summary (Padres Top 10):
Current Organizational Rank: 2^nd
Overall Future Potential: High 6; first-division regular/all-star
Realistic Role: High 5; above-average regular

Renfroe is a personal favorite to watch, he’s big—country strong—kicks up a cloud of dust behind him when he runs, and has hands that make the handle of his bat look like a toothpick. His natural strength is evident in his swing which showcases good bat speed without forsaking balance and repetition.

The initial movements in Renfroe’s swing are strong. He uses a double-tap stride ala Chipper Jones while keeping everything nice and controlled. Even though his front foot taps back, his overall weight never sways behind his back foot. One moments that really stands out in his swing is how his hips start to coil and move forward right as his foot is finishing the first tap. This puts his lower body in a great position to transition to the rest of his swing.

His lower body works very well throughout his swing, the more I watch Renfroe, the more impressed I’ve become with how he uses his lower body. It’s slow and controlled enough to help out his timing while still being explosive and well timed to allow his natural power to flow. Renfroe is a great model for hitters on how to use their lower body without any big, obvious moves, like a Jose Bautista leg kick or Bryce Harper back foot action.

Renfroe’s upper body is mostly good as his hands sync up well with his lower body and he avoids any serious red flags with how he moves. There is a moment after his front heel plants and his upper body has just started to turn when his hands lag just a bit. After his front foot lands there is a gap between his hands and back shoulder, this means his hands flatten out a bit later than most hitters making his contact window more out in front than is ideal.

But no need to worry, Padres’ fans, Renfroe’s overall swing is very solid. The hit tool will be average and the power is plus. There’s going to be some swing and miss in his game, but Renfroe still has middle of the order impact.

Corey Seager, SS, Los Angeles Dodgers

Seager looks like the shortstops from the 90s and early 2000s. He’s big and puts a charge into the baseball with a strong compact swing. Seager comes from a family of hitters and it shows in his swing. He tore up the minors this year, but the question remains: is this a swing built for big-league success? Overall, it appears the answer is yes.

His upper body is about as close to textbook as you will see in the minors. He has a small, controlled load of his upper body that puts him in an excellent position from which to launch the bat. It’s an impressive action, but not all that rare. What does set him apart is how his upper half moves as one unit rather than a series of parts, which makes his swing extremely repeatable. Hitters are always trying to tweak something, but Seager will have far less fix.

His lower body is solid, but it’s not the picturesque pattern of his upper body. He uses a small double tap similar to Renfroe and as he taps back there is the tiniest bit of sway backwards with his upper body. Nothing major, but it’s an unnecessary movement that doesn’t add anything to his overall swing.

It’s not that Seager’s pattern is bad, but he’s not maximizing his lower half. At the beginning he doesn’t get into his hips as much as he could, and at the end he doesn’t put himself in a position to clear his hips as much as possible. In BP his front foot is very closed off, while in games he almost rolls that foot when he really cuts his swing loose. Landing with his front foot a bit more open would eliminate that roll and allow his hips to clear more consistently.

Try and throw a baseball with a closed front foot. You will have to fight your hips to fully rotate. The same principle applies for hitting.

Seager will continue to be a great hitter with his current swing. His upper body movement is awesome to watch so it would not be a surprise if his lower body follows suit over the course of his development. It’s clear that Dodgers fans have something special to look forward with when it comes to the offensive potential of Seager.