"Playing the concussion card?"
We KNOW that NFL players are more at risk for concussions than the average person. We also KNOW that concussions in the past make you more likely to have a concussion in an impact/force to the head incident.
And most NFL players have had a concussion at some point.
When I was in college my roommate got into a car accident, someone T-boned him. Somehow, he drove that thing home. He was not drinking or doing drugs, but he does not remember the accident or even driving home. In fact, he found out about the accident the next day when I pointed out what happened the evening before. He absolutely had a concussion and it completely affected his memory of the incident as well as his actions after.
It is very likely that happened to Coleman, or at least it is very possible.
To me, walking 2 blocks and flagging down an officer is hardly "running away". It is absolutely plausible that Coleman might have lost his reason after the accident, and it is very possible that part of the problem is he cannot remember the accident to defend himself (as shared, I watched this very issue happen with someone else I knew that was in an accident).