Everyone is different, but in general the human body can only build muscle but so fast. I'm not a scientist or a doctor - but I'm a gymrat so this is my experience.
With a perfect diet(I assume he's getting this), a perfect workout routine(I assume he's getting this) and lots of rest(I don't know if he's getting this, millionaire 21-22 year old.. probably not getting the most sleep) - it is somewhat possible to gain that amount of muscle... in a year. I'd say you can put on 8-15 pounds of muscle in a YEAR. Anything more is probably water weight from your supplements and creatine in my experience. In such a short time frame(Draft to training camp) - he could probably put on 4-8 pounds of muscle, and I'd say more likely the 4ish range. Without T-drops, PEDS, etc... the human body is just kind of slow.
Let me say again to all CZ readers: the clinical research on the use of creatine, steroids, vitamins, supplements, herbs, and excess protein is all negative over the long term. Unfortunately, FB players, other elite athletes, and amateurs as well feel the need to try anything and everything in an attempt to gain an edge. It's obvious that there are long term consequences to the battering that one gets in FB, but there's no sense adding additional risk to that.
Studies are ongoing to determine the reasons for severe neurological decline in some but not others after being subjected to the same amount of head trauma. It's quite possible we'll learn that the use of some so-called performance-enhancing substances contribute to this decline.
One can use Staubach as an example of excellent neurologic function despite multiple concussions, then seek to determine the influence of other agents which may co-operate in the debilities that we have seen.
Moreover, there are hepatic and renal consequences of substance overusage which show up later in life, by about 50.
It's likely that by the age of 60, we may wish we'd taken better care of ourselves, and that includes everything we put in our bodies.
