Reasons to where a helmet when facing bowling machine

Ex- Kent CCC opening batsman David Fulton is struck in the head by a ball from the bowling machine in the nets when least expecting it! It's a shocking incident. Book at net today at Glenrothes Indoor Cricket Centre, see http://www.glenrothescc.co.uk/news/indoor-cricket-centre--lanes-now-only-10-per-hour-1284332.html for info.