In HS/college I did my share of full-contact sports. Getting knocked hard can leave you staggering around like a drunk for a few seconds afterwards. That's with young prime health + wearing pads so you don't have any specific injury.
If you get hit really hard they will have to stop the play and help you off the field. It might not be a concussion (or it might) but your whole body gets sort of "concussed" if the hit is hard enough.
Sometimes people say "I got the wind knocked out of me" because of a specific hit to the solar plexus that temporarily disrupts your breathing (if that happens to you, you won't ever forget it). But other times people say that because their body is just rattled and they need a few seconds/minutes to reboot.
As you get older the incapacitation period gets longer. Now in middle age, after a hard hit it might take me a minute or more before I'm ready to re-engage with the activity. Again, that's without any specific injuiry.
This.
+1