What makes a homerun

If a pitcher can locate a slider right at the knees, even if it is in the strike zone, there is essentially no chance of it leaving the park. But the chance of a home run increases quickly as pitchers leave them higher until just above the belt, where it becomes the easiest pitch to hit out, but then surprisingly falls off towards the top of the zone.

Here it is important to split up the handedness of the pitcher and batter, as a slider that ends up low and away follows a completely different trajectory when coming from a lefty than a righty although it turns out the final results are not as different as you might think.

They show results for right-handed batters against right-handed and left-handed pitchers, respectively. As you would expect, the matchups that favor the batter result in a higher home rate across the board, but it seems much important where the ball ends up than which side of the mound it was released from.

Hitters prefer a pitch slightly inside, which they can pull. If you hit the ball straight up, it spends quite a bit of time in the air, but doesn't travel far from home plate. If you hit the ball horizontally, as in a line drive, the ball moves away from home plate at maximum velocity, but quickly hits the ground because of gravity -- still not very far from home plate. To maximize your hitting distance, you need to have both a high horizontal velocity AND you need to keep the ball in the air for a longer time.

You can do this by hitting the ball at an upward angle. Some ballparks are smaller, have higher walls or have different wind currents. This means home runs in certain ballparks might have stayed in the yard in others. The term "home run" comes from the basic act of a batter circling all the bases successfully.

In the early days of the home run, running was typically a necessity as players weren't very powerful and outfields were much bigger, leading to a greater number of inside-the-park home runs.

Now, however, most home runs feature players trotting around the bases after hitting the ball over the fence. But composite as well as metal bats are hollow. When the ball impacts them, they squish down a bit and then—and this is key—they bounce back out, returning some of that energy from the compression back into the ball.

What you really want to know is the moment of inertia, which is essentially where the balance point of the bat is. Two bats with exactly the same total ounces can have very different moments of inertia and will feel different when you swing them. An end-loaded bat is harder to swing, whereas balancing the weight towards the handle makes even a heavy bat feel lighter, and thus you can swing it faster and control it more easily. To figure out the moment of inertia on a bat, you can try to balance it on one finger.

Since your goal is to hit the ball as far as possible, you want the air to help you out as much as it can. Dense air produces more friction with the ball, slowing it down, so diffuse air is best. All these changes probably only give you a few feet more, but that can be the difference between a pop fly and a homer. For even more help, having even a five mile per hour breeze blowing the ball toward the outfield can tack on another 18 to 20 feet.