The umpire has lots of discretion. An ejection could well occur if the contact was intentional, but it wouldn't happen if it's an accident while, say, an fielde

The umpire has lots of discretion. An ejection could well occur if the contact was intentional, but it wouldn't happen if it's an accident while, say, an fielder is chasing a fly ball faster than the umpire can get out of the way.