A bloke i play with doesn't wear a box, his reasoning being "i've never worn one before."
He got hit in the nuts once in a friendly much to the amusement of the rest of the team. Two balls later, bang, straight in the onion bag again! Still doesn't wear one!
I've bought an ayrtek one for this season as i've been using my old box for hockey (which i've been roped into playing). Haven't been hit yet! Though last year i had one belted into them during catching practice and i couldn't walk for about 2 days, it was a worse pain than breaking my ankle! Would never play without one.