It was by no means a D1 college level pace, but back in HS I had a similar injury where I landed on my back and my head swung back and hit the court hard. I had extremely bad whiplash after and couldn’t move my head side to side at all for a few days, but no concussion. Then another time I literally gently ran into a guy and got a concussion. Point is, it’s hard to tell at first glance, sometimes you hit your head just right or you don’t, shouldn’t jump to conclusions until the team has time to look at him and make an official report.