Raffl is entering his prime, and his advanced stats consistently have him as our 6th best forward, and it wasn't a product of playing with G & V, he's got solid advanced stats this year bouncing around lines.
He's limited offensively, but he's not a black hole. Otherwise he's a solid forward who provides flexibility, something undervalued in an 80 game season until you watch the Flyers go with 1 decent line for half the season. He can play with Couts and make that a great possession line, then move down to the 3rd or 4th line if they land or develop a LW who deserve to play on the 2nd line.
What Raffl does which is grossly underappreciated is the "dirty work," he'll chase the puck into the offensive zone, go into corners, fight for the puck and keep it in the zone - as we add more talented offensive defensemen that trait becomes more valuable - as long as he keeps opportunities alive, someone else can finish the job.
One reason his stats aren't impressive is he doesn't get any PP time, guys like Hartnell weren't much better offensively ES (because he had to be set up by his linemates, Raffl makes plays happen), and were far worse defensively. Raffl is the kind of winger who effectively eats up ES time, freeing other top wingers for PP duty.