Leaving Laf aside for a moment, Panarin and Strome have to grow up. Strome even more so. What they need from their 3rd linemate is asking too much. They need the linemate to go in and dig pucks out of corners because neither seem able to do that with any consistency. They need their linemate to then always be the first man back. Always be F3 because they rarely hustle back on the forecheck. Often caught in deep and then both act like wingers from the 1970s where they basically just try to cover the trailing D. (as long as those D dont bother to join the rush of course!) Not only do we need more complete games from these two but we need to take kakko off that line.
Kakko is our best forechecking boardworker. He needs to be able to play in the corners and with the puck. And he shouldn't be tasked with having to always be F3. It's impossible to be both the guy digging out pucks and first guy back in every situation. Playing with P&S also greatly minimizes Kakko's touches on any given shift. Kakko is a possession guy. He needs to be with Zib/Kreider or Chytil/Blais/Gauthier/Hunt/Goodrow. His game will flourish with those configs.
As for Laf? I don't think he should be tasked with the responsibilities of being F3 on that Panarin line. That said, because he's a bit shy on the forecheck, its possible he could be decent at being F3. But his ability to dig out pucks is not great so I would think Goodrow is the ideal linemate. I would strongly consider that. The other possibility is bringing up Barron and putting him on that line with Strome/Panarin. Barron is being groomed as a C, but boy would he be an interesting compliment on that Strome/Panarin line. The question is, when he plays wing what side does he play? Honestly Kravy would be better in this spot. Truly. But well, Kravy gotta Kravy