Ever since 2014, the number of home runs hit in a MLB baseball game has risen 47%. While some blame PED's, it is easier to prove the physics. The primary factor in hitting a home run is bat speed. For every 1 extra mph of bat speed, means an extra 1.2 mph of ball speed making the ball fly 6 feet further. Also, launch angle effects whether or not a hit is a home run. The best launch angle is somewhere between 25 and 35 degrees. If the ball is hit on the upper half, it will be a ground ball with a downwards velocity. Lastly, hitting the ball with the sweet spot of the bat (5-6 inches from the end of the bat minimizes the vibration of the bat and thus maximizes the energy transferred to the ball.
Players now are taught to try and hit the ball just below its center to create more home runs, and as a result, strikeout and most importantly fly out perentages have sky rocketed since 2014.