I don't think it's 'definitely' a concussion.... but agree his reaction sure as hell looked like that was the case to me.
Also disagree on what it takes to go thru concussion protocol... with the admission that I can't quote the NFL procedure for doing so... but with 'concussions' being at the forefront of concern today, as far as injuries, it's my understanding that anything, and I mean ANYTHING, involving the head and the concussion protocol procedure kicks in. IOW... I think anything involving the 'head' and concussion protocol is automatic, whether or not any immediate 'visible' sign is apparent. - JamesJM