Exit velocity and launch angle are the two most important factors in how far a ball will travel, but the spin of the ball also plays a role. A ball with backspin will go farther than a ball with no spin or a ball with topspin. For this reason the ideal home run swing is slightly more level than the incoming angle of the pitch, thereby imparting backspin on the ball. Also, I have read that bat speed is the biggest factor in exit velocity but pitch velocity also comes into play. The faster the pitch, the faster the rebound off the bat. I've said this before, but I think there will come a time when Miguel Sano will connect with a 98-MPH pitch and hit a fair ball over the third deck at Target field.