A 2-year study looking at mild traumatic brain injuries (MTBI), or concussions, in Major League Baseball and the minor leagues reveal some interesting statistics. There were 41 reported MTBIs in the major leagues and 266 in the minor leagues. The overall MTBI game rate across both major and minor league ball clubs was 0.42 per 1000 athlete-exposures. The median time lost was nine days. Mild traumatic brain injury accounted for 1% of all injuries resulting in time lost from play.
Source: American Journal of Sports Medicine, May 2015