Yasuo Ult Bug

So, I was playing a game with a friend today, Summoner's Rift, normal queue, etc. The enemy team had a Yasuo (as they almost always do) and a blitz, and my team... well the members don't really matter. I'll make this short.

1.) Teamfight brewing, hasn't quite started yet. 2.) We're defending near turret, their team is a little bit away but 3 of them are still on the screen. 3.) Blitz throws a grab, catches Quinn, Power fists her, Yasuo ults. 4.) 3 other people of my team immediately follow up to attack Yasuo & co. while he's ulting, but get this.... 5.) As soon as they step near Yasuo's ult, they quite literally get picked up and added into it, hit by his 3 second CC and losing most of their health bars instantly. 6.) Yasuo, of course, proceeds to clean up, etc. etc.

Now, Blitz and Yasuo were the only two champions on the enemy team with a displacement for Yasuo to ult off of-- and Blitz had already used his Grab/Power fist and Yasuo was in the middle of his ult. So how in the world did the other 3 members of my team get... ADDED to his ult? They were simply standing close to him, but didn't get cc'd or anything.

I've only had this happen once before, so I dismissed it at first. But now that this has happened again-- and led to Yasuo getting an instant Quadrakill, can anyone tell me if they've seen this as well/can reproduce it? And if this is an actual bug (I hope to goodness it is, because getting added to Yasuo's ult simply by standing next to him during it is adding Extremely OP to OP), hopefully we could get a Rioter to notice this so they can fix it.