The advice to hit the ball on the ground is something that I have heard uttered by coaches and hitting instructors for years. This is the same advice that I was given throughout my career from tee ball through pro ball. This is also a phrase that I wish could be retired forever, simply because the numbers throughout the history of baseball do not support it.
The coaches who preach hitting the ball on the ground are the same ones who advocate for having a super short swing and swinging down on the ball, thus creating ground balls. I believe the rationale is that ground balls are harder to field than fly balls, therefore hitters will have a better chance of reaching base. Or, it could be that if you just simply put the ball in play, you will avoid strikeouts. However, there is a reason that ground ball pitchers are such a prized commodity in baseball and why hitting the ball on the ground is so much more advantageous for the defense than the offense.
Below are the numbers for all batted ball outcomes during the 2013 Major League Baseball season which are similar across other years.
Batted Ball Type OBP SLG OPS
Grounders .232 .250 .483
Liners .685 .883 1.568
Flies .213 .621 .834
So, if you look at the numbers, obviously hitting line drives are best. A proponent of hitting the ball on the ground would show how the on-base percentage is higher than hitting a fly ball. However, the .019 advantage in on-base percentage is not even comparable to .371 difference in slugging percentage. This difference in slugging percentage is due to the fact that it is very difficult to get extra-base hits when hitting the ball on the ground. The only real way to get an extra base hit when hitting the ball on the ground is to hit the ball hard down the line, a hit that does’t happen very often.
The fact is that the most successful hitters are the ones who are able to produce runs. Below are the amount of runs produced from each type of batted ball per out.
Line drives: 1.26 runs per out
Fly Balls: .13 runs per out
Ground Balls: .05 runs per out
This data shows how much more productive hitting the ball in the air is versus hitting the ball on the ground is. Fly Balls produce more than two times the number of runs than ground balls.
Now, the data presented does only show the major league data, where power is a much more prevalent part of the game than at younger levels. Also, better field conditions at higher levels make fielding ground balls a little easier. However, we never want to try and hit the ball on the ground, because the swing that would require consistent ground balls would be on a downward plane, not an upward plane as shown below. Taking the correct bat path, with a slight upward path, will keep the bat on the same plane of the pitch longer and give the hitter the best chance of making good contact. This path will also produce many more fly balls and line drives.