He just moves so much offensively compared to the likes of Busi/Rakitic. It's night and day when comparing those two to Vidal and Arthur, who are always in motion. That raises the involvement level of our other players like Dembele, Semedo, and most importantly Messi.
Only one of Rakitic or Busi should be starting for us IMO. Arthur and Vidal represent a true change from the style of midfield we've used for the past several failures in the CL. I think that it doesn't need to take anything more than basic tweaks to our lineup and strategy to win the CL if we can pull out these kinds of performances when it matters on the road.