I hope he comes back to track by the late spring. He was probably hoping to be a higher round draft pick, which is not a stretch for a star wide receiver on a top team (or what was a top team) in the Pac 10. The contract value, signing bonuses, and guaranteed money drop precipitously in the NFL as you go down from the top through 19 (guaranteed contracts) to the second round, to the third round, and below. Third rounders might get about $2 million contracts over four years but very little guaranteed. So, he could have hit it really big but he could also have gotten a knee injury on that level, if he made it, and lost his contract, with very little guaranteed.
http://www.businessinsider.com/nfl-draft-contract-values-2016-4