Kopitar's production dropped from 92 to 60, Iafallo's production hopped from 9 goals 25 points to 15 goals 33 points.
He's now a third year pro who ripped it up in college as a late bloomer too, I don't understand how everyone wants to put a ceiling on him before this year is over.
While I agree with both you and @BigKing that in a perfect world he'd be on the third line or so, we're not in a perfect world, and he's certainly not hurting the top line, and I'd argue he's helping it a lot more than he's getting credit for.
(I would also follow whoever's suggestion it was in putting Grundstrom a tryout up there too)
I speak for myself on this, but I feel he absolutely does. A better offensive threat be it the guys I named would score on 50% of Iafallo's chances, that mind you are usually prime opportunities.
You're falling for a trap in thinking that his increase from 25pts to 33 pts was impressive. He literally whiffs on 60%-70% of his opportunities and surprisingly he is almost guaranteed to hit anything other than the open net. Kopitar's offensive drop last season was big no doubt but the majority of those points were from his hardwork and nothing more, people keeping missing this but after his single digit totals the first 20ish games or so he finished at damn near a PPG.
Iafallo is along for the gravy train on Kopitar's LW and nothing more, His ceiling is in fact as a 3rd liner, his shot is Charmin soft and for all his hustle he just doesnt have the talent to warrent being in that position. Thats said, he'd look good on a line with Lizotte and Carts but again this is just my opinion.