Change of position

There is a reason there has only been 2 players in the past 30 years show they are capable of being forwards and defencemen, because it's almost impossible to do well.
Burns and buff were able to because they were massive and just did a very very simple crash the net offence style with no game outside of that. Rielly is not that guy

Problem with Rielly on the wing is he can't shoot. He'd be closer to a Kerfoot than a Nylander or Marner.

There ability to get in your face as defense translated to getting in on the puck carrier. Rielly hasn't shown any signs of being a good forchecker or net front guy

Yep, big guy with some wheels and hands who could park himself in front of the net