I would probably advise against it. They don’t allow you to take in footballs/baseballs into the stadiums here, nor Frisbees (I saw people have to toss out a football they had brought in, yet you can buy them once you’re inside the stadium).
Not sure if all the stadiums are consistent across the US but Oakland CA…kind of a rough area to begin with, so not sure if their security is intensified…
Plus, there is literally no room to move around anyway, even if you’re as careful as you can be, there’s still a huge risk in accidentally clobbering somebody (and if they’re drunk…prepare for madness).
Different location but I had been asked to keep the yoyos put away when I went to Disneyland, when going through security. Disney is also a bit too crowded to try yoyoing, though I still resorted to using a short-stringed Mighty Flea which sparked up some conversations in line 
