You think it's impossible for a professional athlete with access to the best trainers/equipment/supplements/et cetera that money can buy to put on fourteen pounds of muscle in three months without using something illegal? That's interesting...
You say the end of the season as if the Kings stopped playing a couple of weeks ago; the Kings stopped playing before the middle of April.
Exactly.
Working out about 6 hours a week, you should be able to add 1-2 lbs. of muscle a week. Adding 14 lbs in 3 months is nothing for someone who doesn't have to go to work, raise kids, etc., and can focus a lot of time on strength training.
But it wouldn't hurt Kev to do a cycle or two of HGH.