Does this cause a concussion?
300
Can a runner get a concussion by a wild throw to a baseman?

Yes, these throws from outfield, and infielders can be 60 mph. These throws can get you a concussion very easily with little protection from a helmet.

400

Does getting hit by a tipped back ball cause a concussion?

Yes, A catcher can get a concussion by a tipped back ball, due to a lack of protection in the catcher mask.