With the disclaimer that I have no access to Gronk, his examination, or his standardized testing scores.....
The Concussion Protocol that the NFL appears to use (from review of the data available on the internet) is no different than the one used in my practice and in most practices that I am aware of in my local area, and this can be broken down as follows:
Recovery:
In this stage, the patient is placed in a "brain rest" protocol. Yes, it means what it says.....you are basically in shut down mode. Rest, fluids, avoiding extra stimulation. Screen time (tablets, PC's, etc.) is limited, limited access to cell phones, no gaming devices - anything that requires a great deal of mental energy and focus is limited. This is all "designed" to allow the natural and physiologic autoregulation processes to "reset". Concussions occur when, as the result of some external force application, there is an uncoupling of the autoregulation of energy supply and demand. In the normal homeostatic state (the way life should be, like ME but a lot warmer with less snow, mud, and black flies), the energy demanded by the brain is supplied - need more get more, need less get less. After a concussive injury, there is a marked spike in the energy demanded by the brain (to repair the microshear injuries) at the exact time when there is a loss of control over the supply side of autoregulation. This is due to a number of cellular processes, well beyond what needs to be discussed here. Suffice it to say, this results in a supply-demand mismatch, and, as there is in a market economy, there is a "premium" to be paid in the form of symptoms as a result. As long as this gap exists, symptoms exist. Headaches, light sensitivity, imbalance, visual disturbances, nausea, etc. can all be symptoms. When the gap goes away, the symptoms go away. The supply side comes back on line over time, and the only controllable variable over the demand side is rest, which will lower demand, minimize the gap, and facilitate recovery. Time and rest are the only "medications" available for the recovery process. From everything that is available, it appears that Gronk is asymptomatic at this time and has "recovered".
Rehabilitation:
In this stage, gradual exercise progression is initiated. Aerobic activity is progressed from light to full intensity, sport specific activities (minus contact) are added, and the patient moves along the steps of the Zurich Exercise Progression provided the previous step has been completed without recurrent symptoms. Basically, this step provides a stress test to the supply-demand relationship to ensure that it is strong and won't we "broken" under an increased external stress being applied (increased physical exertion). Upon successful completion of this step, there is only one hurdle left to clear. Gronk seems to be starting this stage.
Repeat Testing/Return to Baseline:
All of these athletes have undergone some baseline neurocognitive testing (locally, it is ImPACT Testing). The testing is repeated and compared to baseline to ensure all parameters are within an acceptable range. Again, this needs to occur without recurrent symptoms. If this occurs, the athlete is returned to full activity without restrictions.
This is all done to minimize the risk of a secondary injury and the risk of the development of postconcussive syndrome. If athletes are returned prematurely, the force required to re-injure and result in more profound symptoms is less - they are more susceptible to recurrent injury. In lab studies, there was less cellular damage and disruption to rat brains when struck with a single 10 lb force in a single injury as compared to 2, 5 lb force injuries in a "stacked" fashion (given in a time window where there was no chance for full recovery to occur). This is the underlying physiology that is seen in second impact syndrome, which can be lethal.
If there are any specific questions after this, ask away and I'll try to answer.