Yandy Diaz needs to change his hitting approach: Between Innings

How do you keep the infielders from being able to get you out? Hit it over their heads.

The refrain is known to many from Little League all the way through MLB rosters as the hitting revolution has come to baseball and it involves obtaining elevation on the batted ball. The current starting third baseman for the 2017 Cleveland Indians though has yet to hear the siren call of swinging on a slightly upward plane. Yandy Diaz continues to kill worms and exercise middle infielders as his hitting profile is obscenely shifted towards keeping the ball on the ground. Despite the muscle-bound behemoth hitting the ball with great force, the results have been a meager 5-for-23 with only a lone walk accompanying the drought upon contact escalating his issue.

WFNY’s Mike Hattery wondered if the public discourse disconnect on the Diaz defensive efforts at third base had more to do with Super-2 status than actual defensive woes. As Diaz has proven quite able with the leather making several nice plays on the hot corner in the limited sample size of the young 2017 season, it remains a possibility. However, a new theory rises in why the organization might have been downplaying the chances on Diaz making the 25-man roster, which he only made due to an injury to All-Star second baseman Jason Kipnis. There is a chance that the Tribe sees Diaz’s ground ball tendencies as an offensive limiting factor, but he has been either unable or unwilling to change. Of course, it is also possible the Indians did not want him to change his profile until having seen what his profile did at the MLB level. The hope here is that they will be working on it now.

This hypothetical comes without direct knowledge of the Indians desires for his batted ball future, but instead from a strongly formed slant among present day hitters adjusting to defensive shifts and attempts by pitchers to keep the ball on the ground alongside the knowledge that home runs and extra base hits are almost exclusively done through fly balls and line drives.’s Mike Petriello had a recent article that dove in on the surge of home runs with a specific focus on the mentality and preparation of MLB hitters moving towards elevating the ball. His hypothesis is not proven through the article, but it is born out through discussions with many players.

What if part of it was as simple as a new generation of analytically savvy players simply trying to hit more homers? After all, we are seeing players talking about trying to elevate the ball, notably late-blooming sluggers like Josh Donaldson, Daniel Murphy, Justin Turner and J.D. Martinez. Not to mention the fact that the average launch angle across MLB rose from 10.5 degrees to 11.5 in 2016.

What is Exit Velocity & Launch Angle
The advent of Statcast has allowed MLB to track information on every batted ball and save the information in a database. Two of the most important pieces of information saved are that of exit velocity and launch angle.

Launch Angle is the vertical angle the ball leaves a player’s bat after being struck. You have always known about them, but you just had different names for what you saw. Ground balls (less than 10 degrees), line drives (10-25 degrees), fly balls (25-50 degrees), and pop ups (anything greater than 50 degrees) are all defined by the angle at which they travel. Statcast has just allowed more strict definitions and to track a player’s overall profile better.

Exit Velocity is quite simple as it is the speed at which the ball travels after being struck. Hard hit balls are more difficult to defend than soft hit balls in general though where the ball is hit and the type of ball hit (see launch angle) plays a significant factor as well.

Why do EV & LA matter?
Professor Emeritus of Physics at University of Illinois Alan Nathan has been a physics of baseball researcher for 20 years. He has posited theories and provided quantitative analysis of why the baseball behaves as it does. Nathan has also become the technical advisor for Diamond Kinetics, which focuses on engineering technological solutions for baseball players. Their work does everything from creating tools to developing baseball drills with the end result being to better train the player’s motor functions for optimal results on the field.

The research to indicate the optimal results therefore is paramount. The focus on EV and LA in order to determine the best type of batted ball has been an important step in the modern hitting revolution. Hitting the ball in the air has proven through data to be a more beneficial result as a whole, but there is even descriptions to where there is failure here such as the donut hole.

The three dimensional chart demonstrates how combining the LA and EV give a hitter the optimal path towards success. Notice as the LA increases, more of the chart is shaded green, yellow, and red indicating a higher BABIP (and more likely hit). wOBA can be graphed with similar results with an even heavier disposition towards increased LA as low-hit balls do not lend themselves to extra base hits.

Back to the donut hole as can be seen on the chart on the right-hand side there is a valley of blue and purple. Balls hit in that range are ones with a higher probability of being caught be an outfielder. Notice there is a peak at 60 to 70 miles per hour at the same LA on the far right. The reason for those are bloopers which fall before they can be caught.

Using this information, Mike Petriello defined a new term called barrels, which refer to well-struck balls where the combination of exit velocity and launch angle generally leads to a minimum .500 batting average and 1.500 slugging percentage.

As you can see, the “Barrel Zone” is an area that begins at 98 mph between 26 degrees and 30 degrees, and expands outward from there. The higher the speed of the ball, the wider the range of launch angle exists for a ball to be considered a barrel. At 99 mph and up, for example, between 25 degrees and 31 degrees is “barrelled.” At 100 mph and above, batted balls between 24 and 33 degrees will always be considered a barrel, and so on, expanding as balls get hit harder. Those aren’t arbitrary definitions; that’s based on a review of all of those batted-ball types and outlining the area where you get your minimum of “.500 batting average and 1.500 slugging percentage.”

What does this mean for Yandy?

courtesy of BaseballSavant

The physics of barrels have been proven out through the data collected. The results are not promising for the current batted-ball profile of Yandy Diaz. The three-dimensional chart from Nathan above demonstrated that there are no peaks of green, yellow, or red below 10 degrees of launch angle.

Exit velocity has not been an issue for Diaz as most all of his batted balls have been above 90 miles per hour though the MLB sample has been extremely limited. The issue lies in that the chart above on the left demonstrates he has not been hitting the ball above 10 degrees often. The propensity of his contact has been from 10 degrees to -20 degrees indicating that he is hitting ground balls. Worse yet, Diaz has given defenses an ability to pinch the middle of the field as his contact has been concentrated so far (seen on the plot map on the right above).

The ground ball tendency is not a new phenomenon to Diaz hitting MLB pitching either.1 Throughout his MiLB career, Diaz has had a ground ball rate of at least 53.5% with a shift upwards overall at the higher levels. In stark contrast, the 2016 Indians had a team ground ball rate of 42.6% with only Roberto Perez exceeding 50% (53.6%).

courtesy of StatCorner

Last Word
A common refrain heard discussing pitchers is for them to keep the ball low in the strike zone in order to help keep the ball on the ground. Doing so allows their infield defense a chance to make a play behind them for the out especially as MLB teams have learned hitter tendencies in order to properly position their defenders. So, it should not be a surprise that hitters are now attempting to do the opposite of what pitchers want them to do. More and more MLB bats are being swung with a specific attempt to elevate the baseball.

The brief stint on the 25-man club might have been the best thing that could have happened to Diaz. He has been provided with evidence to why his ground ball tendencies will not play at the MLB level. As Jason Kipnis prepares for his return, a move back to Triple-A Columbus could afford Diaz the opportunity to make some adjustments to his swing in order to maximize his abilities.

There is hope for Diaz as with some adjustments to his swing plane, he could become the next late-blooming J.D. Martinez or Josh Donaldson.. His bat speed is electric, which has been helping him achieve desirable exit velocities on batted balls. Someone just needs to help him elevate the freaking ball.

  1. Hat-tip to Kevin Dean for the assist on obtaining Minor League numbers through []