I once had a buddy of mine, who at the time was rather asthmatic, blow a ball, with his mouth, through an old rifled barrel (meaning it had real lands and grooves, so nowhere near a perfect seal) which hit me on a puffy, down jacket... and it broke. Range was probably six feet or so, and it was cheap PowerBall.
No bounce, it didn't crack and fall off leaving a small mark, I mean it made a full splatmark on my soft jacket. We were both pretty surprised.
On the other hand, there was that one time we saw some Polar Ice bounce off of concrete...
It all depends. Does it hit on the seam? Does it have a weak seam? Is it brittle paint? Is it cold? Has it been stored properly? Has it had a chance to soak up some humidity? Is it hitting something soft? Something hard?
I've had a ball fly out of nowhere, moving slow enough to catch, land on a fold of my jersey and break, and I've had nearly point-blank shots bounce off my mask. You never know.