Kagan: The physics of the ‘seamy’ side of baseball

From SABR member David Kagan at The Hardball Times on January 17, 2020:

The Preliminary Report of the Committee Studying Home Run Rates in MLB (December, 2019) released at the Winter Meetings in San Diego makes the droll statement, “The aerodynamic flow over a baseball is complex…” Nonetheless, it has provided much more solid data on the effect of seam height on the flight of the ball but still must acknowledge “only 35% of the increase in home run rate attributable to greater carry is due to a change in the seam height.”

The seam height is a feature that clearly disturbs the surface smoothness of the ball. One would suspect, based upon “common sense,” that anything that disturbs the smoothness would cause the air flowing over the surface of the ball during flight to impede the progress of the ball. However, this is not always the case.  

A golf ball is the usual counterexample. The dimples on a golf ball allow it to travel through the air more easily than a non-dimpled ball. The data from the report clearly shows that for baseballs at game speeds and spins, the “common sense” idea applies–the lower the seams, the further the ball flies. Thank goodness.

Read the full article here: https://tht.fangraphs.com/the-physics-of-the-seamy-side-of-baseball/

Originally published: January 23, 2020. Last Updated: January 23, 2020.