Getting Under The Ball Like Stephen Vogt – A Baseball Swing Plane Experiment


Baseball Swing Plane: Stephen Vogt

August 2014  Stephen Vogt (21) hits a solo home run. Mandatory Credit: Kyle Terada-USA TODAY Sports

Stephen Vogt side note: CLICK HERE to watch video of him doing referee impersonations, he’s apparently known for, on Intentional Talk.  That’s Johnny Gomes in the background 😀

Question: Can the Back Leg Angle Affect Ball Flight During the Final Turn?

Using the Zepp (Labs) Baseball app, I wanted to use the Scientific Method to analyze the effect the back leg angle has on ground balls, line drives, and fly balls.

Background Research

Two posts I’ve written that talk about the back leg angle:

In the above posts, pay particular attention to what Homer Kelly says about Knee Action.

As of the beginning of May 2015, Stephen Vogt of the Oakland Athletics, is ranked 2nd overall in OPS at 1.179 (according to’s sortable stats).  Can he hold this up all year?  Maybe, maybe not.  But the metrics I’m about to reveal have a solid base in his back leg angle mechanics.

He has a very distinct back leg angle during the Final Turn and follow through (see image above).  Here’s how his metrics stacks up over four seasons, against the league average (according to

  • Ground ball% – Stephen Vogt (32.6%), League Average (44%)
  • Line Drive% – Stephen Vogt (20.7%), League Average (20%)
  • Fly Ball% – Stephen Vogt (46.6%), League Average (36%)
  • Home-run/Fly-ball Ratio – Stephen Vogt (10%), League Average (9.5%)

So he’s well below the league average in ground-balls, slightly higher in line drives, and has  a 0.5% higher home-run to fly-ball percentage.  The latter meaning what percentage of his fly-balls go over the fence.  Lastly, as you can clearly see, Stephen Vogt has an above average fly-ball percentage.  Remember, fly-balls aren’t always bad.  Most times, they’re more productive than ground-balls in sacrificing runners over or bringing them in to score.



Based on the above research and with my own experience, I think that having the back leg angle bent in an “L” (or 90-degree angle) during the Final Turn and follow through will produce more elevated line drives and fly balls.  Whereas a straighter back leg angle (closer to 180-degrees) will produce more low level line drives and ground balls.


Baseball Swing Plane Experiment: “Staying Low”

Babe Ruth Hand-Tension Experiment Setup

Here was how I setup the experiment “work station”

Equipment Used:


  • Yellow dimple ball feedback markers = my bat length, plus two baseballs
  • Distance from plate = end of the bat touching inside corner of plate, and knob of bat touching my mid-thigh.
  • Tee was set slightly behind the front feedback marker, and tee height was about mid-thigh.
  • First 100 baseballs were hit with a 90-degree back leg angle during the Final Turn and follow through.
  • Second 100 baseballs were hit a straighter back leg angle (about 170-degrees) during the Final Turn and follow through.

Data Collected (Zepp Baseball App Screenshots):

Baseball Swing Plane Zepp Experiment: "Staying Low"

Fig.1: Here are the averages of both sessions. Pay particular attention to the “Bat Vertical Angle at Impact” and “Attack Angle” preferences…

According to the Zepp app user guide, let’s define the following terms:

  • Bat Vertical Angle at Impact – This is the Vertical angle (Up or Down) measured in degrees, of your bat barrel in relation to the knob of the bat, when it makes impact with the ball.
  • Attack Angle – Attack Angle is the direction the bat barrel is moving (Up or Down) at impact. A positive number would mean your barrel is going UP at impact, zero is LEVEL and a negative number is the barrel going DOWN at impact.

Check out the ground-ball, line drive, and fly-ball comparison:

Baseball Swing Plane Experiment: Ball Flight

Fig.2: Check out the difference in ball flight between the two sessions. Pay particular attention to the ground-ball percentages.

Data Analysis & Conclusion

I wasn’t paying too much attention to bat and hand speed on this experiment.  I only focused on the metrics indicating a change in ball flight.

  • Attack angle had a 3-degree difference according to Fig.1.
  • Bat Vertical Angle at Impact also had a 3-degree difference according to Fig.1.
  •  27% difference in ground-ball% according to Fig.2.
  • 24% difference in fly-ball% according to Fig.2.


Baseball Swing Plane Experiment: Cage Labels

This were the rules I used for ball flight in the cage during the Experiment.

  • Here’s a picture (image to the right) of the cage I hit in and the labels for each batted ball outcomes.
  • I’m not sure why the Bat Vertical Angle at Impact was larger for the “Straight Back Knee”.  Maybe it had to do with my back knee starting bent towards impact, but then the barrel compensated by “pulling up” to accommodate the straightening back knee.  This disturbance in the pitch plane is NO bueno.
  • I found myself reverting back to old habits (Bent Back Knee) during the Straight Back Knee session.  There were at least a dozen balls I hit that had more bend than I wanted during that session.
  • During the “Bent Back Knee” session, about 65% of my fly-balls were “shots”, and didn’t hit the back of the cage to be considered a line drive.
  • I find with small sluggers like Stephen Vogt bend their back knee between 90-105 degrees during the Final Turn.  With fastpitch softball, the angle of the back knee isn’t quite so drastic because of the reduced plane of the pitch.  If I can get my softball players to be 105-120 degrees with the back knee angle, then I’m happy.


In Conclusion

So the back knee angle during the Final Turn does have a significant impact on ball flight.  More bend equals, more airtime for the ball.  I’ve seen Little Leaguers to Pro hitters straightening out their back legs.  And they often wonder why they aren’t driving the ball.

In terms of driving the ball like Stephen Vogt, think of the back leg angle as angling your body like a “ramp”.  Also, take a look at smaller sluggers (6’0″, 225-lbs on down) like: Adrian Beltre, Stephen Vogt, Jose Bautista, Josh Donaldson, and Andrew McCutchen as great examples of back knee bend.

Michael Brantley: How-To BOOST BABIP

Michael Brantley: NEVER Worry About Batting Average Again


Michael Brantley: How-To BOOST BABIP

2014 Michael Brantley photo courtesy:

Last week, I received a question from Brian Petrick that birthed this post:

“What do mlb players need to do to hit for a higher avg consistently and cut down on k’s. Not many .300 plus hitters today.”

I have to thank my Sabermetrics friends at – namely Richard Bergstrom – for introducing me to a key metric that better measures how consistently a batter hits the ball rather than Batting Average.  Enter BABIP. says this about BABIP:

Batting Average on Balls In Play (BABIP) measures how often a ball in play goes for a hit. A ball is “in play” when the plate appearance ends in something other than a strikeout, walk, hit batter, catcher’s interference, sacrifice bunt, or home run. Several variables that can affect BABIP rates for individual players, such as defense, luck, and talent level.”

In this video post, we’re going to analyze:

  • Why analyze Michael Brantley (lefty hitting outfielder of the Cleveland Indians)?
  • What’s the difference in his 2013/2014 swings? AND
  • How can he improve his repeatable power?


Why Analyze Michael Brantley?Michael Brantley 2013-2014 Key Offensive Stats

According to he’s 6 foot, 2 inches, 200 pounds.  Not a big guy by today’s standards.  2014 was the first time he was selected to the American League All-Star team.

Michael Brantley’s 2013-2014 stats were a perfect example to answer Brian Petrick’s question from earlier (photo of stats to the right)…

  • 138 point jump in OPS (On-Base + Slug%),
  • BABIP has gone well above average,
  • GB% went down, LD% went up, and FB% went down, while
  • Home-run to fly-ball% more than DOUBLED!
  • Walk% went up, and
  • Strikeout% almost cut in half!

Yes, according to my stat table, the 2014 season isn’t done yet.  But the amount of “hits” he accumulated in 2013 (158) is virtually the same as 2014 (151).  Hits are a major part of the BABIP equation.  So, what is he doing differently with his mechanics?

What’s the Difference in his 2013/2014 Swings?

Michael Brantley 2014 contact position

Michael Brantley photo courtesy:

After Brian Petrick sent me that question, I obsessed over how-to build consistency into a hitter’s swing (increase BA & BABIP) that could also cut down on strikeouts.  My hypothesis was to get the barrel on pitch plane EARLIER (closer to the catcher), which would translate to more margin for error afforded by the batter.

Take a batter being late on a fast-ball, for example:

  • If the barrel entering the impact zone is closer to the catcher, driving the pitch to the opposite field is an option.
  • However, if the same barrel enters the impact zone closer to the pitcher, the hitter is more likely to swing and miss or hit the ball weakly.

Both Michael Brantley’s 2013 & 2014 swing videos show he’s entering the pitch plane closer to the catcher, and staying long through impact.  But upon closer inspection, we can see he’s “staying shorter” longer through the Final Turn, in 2014.  It looks like he’s
“standing up” in his 2013 swing.

You see, the torso sets the upward swing plane, NOT the hands.  By bending his back leg more at impact (around 10-degrees closer to a right angle than in 2013), makes a HUGE difference in consistently staying on plane of the pitch longer.  Take a quote from page 36 of Homer Kelly’s book, The Golfing Machine:

“A rotating motion will pass through a given point if the axis is tilted properly, instead of having to apply a compensating vector force to drive the rotating element off its normal plane towards the desired plane line.”  

Homer Kelly, an aeronautical engineer for Boeing back in the 1930’s, applied scientifically proven human movement principles to the golf swing.


How Can he Improve his Repeatable Power?

Michael Brantley: 2013 contact position

2013 Michael Brantley photo courtesy:

According to, Zip (U) and Steamer (U) statistics predict Brantley will hit 20-21 homers in 2014.  This would double what he did in 2013.  The same predictive stats show he’ll finish between .846 to .849 in OPS (On-Base + Slug%).  Conservatively, this would be a dramatic 118 point rise!

With the following FOUR mechanical tweaks, we could see Michael Brantley – with his body type – hitting over 30 homers per year:

  1. Forward Momentum,
  2. More downward shoulder angle,
  3. Showing numbers better, and
  4. Hiding hands from pitcher more.

You saw the difference bending the back leg more at impact does to key offensive numbers like BABIP, BA, and Strikeout%.  Also just as important is how close to the catcher a batter’s barrel enters the pitch plane, and how well his “stay through” is after contact.  Brantley already does these well.

However, at the very least, if Michael Brantley engages the natural springy fascial material within his body (mechanical tweak #’s 2-4 from above), then he can be one of the top-10 hitters in the league!