The Kansas City Royals chose Kyle Zimmer out of the University of San Francisco with the fifth overall selection of the 2012 draft. He was the second pitcher off the board, following LSU's Kevin Gausman, and he earned the distinction of having my favorite delivery of the opening round. Zimmer rose to the Double-A ranks in his first full season of pro ball, where he dominated for a handful of starts before he was shut down in mid-August due to stiffness in his throwing shoulder.
























The timing of his shoulder flare-up was such that he missed only the last couple of weeks in the minor-league season, and the Royals decided not to push their prized prospect into action given his proximity to a preset innings threshold. The right-hander had his share of ups and downs in 2013, though his path did not follow the proverbial roller coaster ride. Instead, Zimmer endured three months of struggle before a sudden spike in performance near the end of June.








4/5 – 6/23








6/29 – 8/14








Strikeouts were never a problem, thanks to high-90s heat and a pair of sharp breaking pitches, but in the first half of the season, Zimmer surrendered a lot of hard contact while suffering from bouts of wildness. He did not earn his first win until June 12, prior to which he had given up five runs or more in each of five consecutive starts. His next start occurred 11 days later, but four earned runs and nine baserunners over six frames left him with another L on the stat sheet. He walked three batters on June 23rd, but it was the last time that he would surrender more than a pair of free passes in a game.

After that outing, it was on. Zimmer was unstoppable over his final eight starts, striking out 63 batters against just eight walks in 44 innings of work. He allowed fewer than two runs in six of his last eight starts, though he exited the final game after just two innings due to the shoulder stiffness. The sterling results mirrored the right-hander's improvements in mechanics as well as pitch command, providing optimism that Zimmer can break the string of high-end pitching prospects from the Royals farm system who have fallen short of the big-league rotation.

The footage available on allows us to trace Zimmer's path through the minors, and I sat down to evaluate a trio of ball games from different points in the season in order to better understand his evolution this season.

April 5th @ Myrtle Beach (High-A)
Zimmer's first two starts of the season were gravy from a statistical standpoint, with 16 strikeouts against two walks and just a pair of runs allowed over 11 innings pitched, but the anecdotal evidence revealed harbingers of impending doom. His first game of the year for the Wilmington Blue Rocks came on April 5 in Myrtle Beach, with five innings of two-run baseball that featured an eight-pack of K's. Zimmer gave up only a pair of hits, but both of the knocks left the yard (it was one of just two multi-homer games on the season). He never pitched from the stretch thanks to the combination of round-trippers and his zero walks allowed, but the clean walk rate obscured a lack of pitch command. He had several offerings that badly missed their intended targets, most commonly with pitches that were elevated, and his catcher offered the occasional reminder to stay low in the zone.

Elevating pitches can be the result of getting into foot strike too quickly, such that the rotational elements are not yet primed for take-off. But Zimmer was noticeably slow with his momentum in this game, and the late arm was tied to an exaggerated delay of trunk rotation. Speed to the plate was one of his greatest mechanical advantages in 2012, so it was very disappointing to witness such a pedestrian pace. The low momentum shrunk his stride and release distance, giving batters a longer look at the baseball. His stride timing was rather consistent, but his 1.1-second time-lapse from leg lift to foot strike was on the slow side of average (which is right around 1.0 seconds), while the magnitude of his forward momentum lagged behind that of his amateur days. A very quick worker, Zimmer wasted little time between pitches, and in some cases he kick-started his motion while the batter was still executing his pre-pitch routine.

Zimmer was pumping a high frequency of fastballs with mid-90s velocity, but his secondary pitches were few and far between. Perhaps he was trying to focus on finding fastball command in his first game of the season, or maybe his secondaries lacked their usual bite. He was able to get the strike-three call on a beauty of a curveball to Rangers prospect Rougned Odor in the first inning, but Odor reaped vengeance in his second at-bat, when Zimmer tried to sneak a toothless slider over the dish.

June 7th @ Winston-Salem (High-A)
Zimmer's tailspin was in full effect in early June, and just days before the right-hander toed the rubber against Winston-Salem, Royals Assistant GM J.J. Piccolo highlighted some of the areas where Zimmer needed to work within his development.

As we start breaking down start by start, his pitch selection needs to get better. He's just not going to be able to out-stuff hitters. He's going through the learning process a little sooner than we expected.

Pitch selection was one of the outstanding notes from his first game, and though Zimmer would mix it up with plenty of breaking stuff in the early going on June 7, the results just were not there. He failed to escape the first inning against a good-hitting Winston-Salem team, giving up five hits, five runs, and a walk and hitting a batter while recording just two outs in the game.

One of the downsides to the footage is that the video quality can be rough, and the feed from this game offered a distant viewpoint that obscured much of the action on Zimmer's pitches. An issue that did arise was that Zimmer's balance and posture were a bit off in this game, such as in the following delivery to White Sox prospect (and fellow 2012 first-rounder) Courtney Hawkins.

Zimmer spent the vast majority of this short outing in the stretch position, so I was unable to make a worthwhile comparison of his momentum and timing to the first game of the season. That said, his timing was inconsistent from the stretch, and his momentum was still well shy of the burst that had generated so much excitement during his time at USF. This element caused me to question the Royals’ development tactics on an episode of TINSTAAPP, given the conventional coaching approach that dictates slowing pitchers down (i.e. “don't rush”) as well as the example of Aaron Crow, another high-end KC pitcher pick whose momentum had suffered in his trek from the amateur ranks to the show. Throw in Zimmer's incredibly quick pace from pitch-to-pitch, which could potentially provide the impetus to invoke the “don't rush” instruction, and I worried aloud that Zimmer might have been stripped of the trademark momentum that had fueled much of his collegiate success.

July 25 @ Springfield (Double-A)
What a difference a month can make, especially in the minor leagues. It is not uncommon to see pitchers exhibit extreme volatility in terms of both stuff and mechanics as they experience the trials and tribulations of the development curve, and Zimmer's ascent to an elite force was tied to adjustments that he made to address the issues of the first few months of the season. He identified the ingredients of his success in an interview following a 13-strikeout performance on July 9th:

I feel like my mechanics are starting to come together. I'm staying on line pretty well, throwing all my pitches in the zone and being able to pitch guys backwards," he said. "I can manipulate my fastball, just been working on attacking the zone more consistently.

All of these elements were on display during his July 25th start against the Springfield Cardinals. It was his second start at the Double-A level, and Zimmer had faced these same Cards in a home start just five days prior, yet the previous exposure did little to help the Springfield hitters. Zimmer pitched six shutout innings (just as he had the previous game), with 12 punchouts and just five baserunners allowed (three hits and two walks). The two-game total included a dozen scoreless frames, six hits, three walks, and 19 K's (with a pair of W's to boot). Even the number on the back of his jersey looked better, having traded his no. 60 with Wilmington for a no. 25 uniform with the Northwest Arkansas Naturals.

The difference was apparent right away. The box score shows that he struck out leadoff hitter Mike O'Neill on just three pitches, which gains significance when one considers that O'Neill was the toughest batter to strike out in the Texas League up to that point in the year. His fastball was up a few ticks from earlier in the season, sitting in the high 90s against O'Neill, and he finished the at-bat with a killer breaking ball that resulted in an ugly swing and a quick turn toward the dugout.

What stood out from my vantage point was that Zimmer had upped the ante on his momentum, with a greater burst to the plate that resulted in a deeper release point. I timed his delivery at 0.9-1.0 seconds from leg lift to foot strike throughout the game, and the sheer speed of movement was noticeably better than it had looked earlier in the year. The improved power helped to line up the gears of Zimmer's delivery, with excellent timing and sequencing of the rotational aspects that had the ball exploding out of his hand. When the timing is right, he is able to maximize torque with incredible hip-shoulder separation, and the result was a fastball that was lighting up radar guns in the 97-99 range and that touched triple digits on multiple occasions.

The improvements to momentum did wonders for Zimmer’s timing and pitch execution, and he was painting targets with his fastball, curve, and slider. When he missed the catcher's glove it was by inches rather than feet, and the dominance of his raw stuff kept hitters off-balance regardless of pitch location. His stretch timing was quicker than that of the windup, but he kept a normal leg kick with runners on base and the timing adjustment was minimal, amounting to approximately 0.1 seconds off of his windup pace. I was also impressed by his pick-off move, with Zimmer holding the ball to lull the runner before executing a very quick move to the bag.

Zimmer faced trouble only once in the game, as the Cards loaded the bases in the second inning. Not one of the baserunners was the pitcher's fault, with all three batters reaching via infield grounders that the fielders were unable to convert into outs—all three hits struck leather, and the official scorer granted two hits and an error. Zimmer had no choice but to do the work himself, and he obliged by striking out the side and squelching the threat.

The video crew did me a favor in the fifth inning, going to a different camera that provided an additional vantage point on the refurbished mechanics. The angle was reminiscent of the viewpoint that I enjoyed from the press box when I worked with the Sacramento River Cats, a familiar look that increased the analytic potential for this game as well as the enjoyment level.

Zimmer registered K's on 11 of his first 14 outs, requiring a modest 67 pitches to reach that point in the game, and he finished with a count of 97 pitches through six frames. He dominated a lineup that was stacked with hitters who carried the platoon advantage, with seven of the nine batters in the lineup swinging lumber from the left side of the plate. His fastball flashed an 8 on the scouting scale, the curve was just as dynamite as advertised, and his slider was the best that I had seen from Zimmer all season. The only thing missing was his changeup, which was surprising considering the left-heavy lineup of Springfield, but el cambio was unnecessary on a day when his primary stuff was so sharp.

Mechanics Report Card









Release Distance




For an explanation on the grading system for pitching mechanics, please consult this pair of articles.

The Mechanics Report Card for Zimmer was quite different in the games that I covered, and the above marks reflect his scores from the late July contest in order to capture his significant upside. The downside still exists for the wheels to fall off the wagon, but 2013 served as a lesson that the right-hander needs his signature momentum in order to optimize all of the elements of his delivery. The ripples of plus momentum were felt on his grades for torque, release distance, and repetition.

Even Zimmer’s posture improved late in the season, though this is likely not connected to his extra burst of momentum—in fact, extra momentum typically throws a wrench into postural stabilization. Zimmer had solid balance earlier in the year, but he had a tendency to bail out with the head somewhat near release point, meaning that he was just a minimal adjustment away from converting his previously-average posture into a plus attribute on his report card. Zimmer is an elite pitcher in the making, provided that he sticks with the delivery that brought him to prominence.

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Thanks for this. Good to have some insight into this bizarre season. Looking forward to seeing what 2014 version of Zimmer shows up.
That makes two of us, Jim, and here's hoping that his excellent momentum is encouraged as he climbs the ladder