The main reason for Rielly's dropoff this year, was his skating has gone down hill. "IF" he is to be on the roster next year, I think the main goal this offseason, is to get that skating speed back up to where it was. If he can get his skating back, and a good first step, it will go a long way in making his game acceptable.
He went from 90th percentile in skating speed, and 94th percentile in bursts over 20mph two years ago, to 78th percentile in skating speed.... It's only a small margin, and his skating is better than most, but he really needs that acceleration back, and his skating overall.
Hard to stop father time, but get the weight down a little, work on foot speed...