I don’t care if you use a stem pad on your polo bike.  I do care if you have un-plugged bar ends or exposed chainrings.  That shit is messed up.  But a stem pad is only gonna save the rider of the bike it’s on.  Nuts and knees.  That’s what likely tags the back of the stem in a crash. 

I wear padded gloves, and a helmet, and now I finally have a stem pad. 

If you want to get one for yourself check out skingrowsback.com from Catt & Jamie of Australia.  They make a bunch of things good for polo players.