many ball joint boots have a weep hole. if too much grease is injected it will come out the hole rather than rib/dislodge the boot. my Moogs have this feature. i can't tell if your grease is coming out of a preexisting hole (looks like a small nipple) or if it's torn. wipe the grease away and check. if there's no weep hole and the boot is ripped, someone put in too much grease.