By movement I mean off the ball movement which indeed I think Rakitic is very good at
What games are you watching that you see this? That is maybe Rakitic's worst trait, he often just sits in open, deep positions and doesn't move off the ball while walking. Then he'll just shuttle forwards at random times. He rarely moves into zones of higher pressure, he rarely ever has non-linear movements (checking in for passes and circling around zones). Him and Busi being so static is half the reason our offense would get so bogged down. And Busi, being the spine of the midfield, has justification for it and has more or less always played this way.
If anything the only times Rakitic moves off the ball are overlapping out wide. Which is really not what you want from your CM. If you see the way Arthur moves off the ball constantly while Rakitic just zones out you can see the clear difference. Rakitic is almost as bad as Messi on his bad days in terms of movement and activity off the ball.
maybe it's a coincidence but with him on the pitch we score goals for fun. Stats should confirm
I don't think it's a coincidence, and stats finally show it. xG buildup per 90 measures how much impact a player has on a possession that leads to an expected goal. Arthur is LEADING the squad in xG buildup per 90 at .87 in La Liga. xG chain is the same stat except including key passes and shots, where Arthur is 5th in the squad (and 1 of those ahead of him is Munir who only played 1 game). Though tbf Arthur only has 87 mins under his belt, but that's over 3 different games so it is not skewed.
For reference Rakitic is at .6 xG buildup compared to Arthur's .87
https://understat.com/team/Barcelona/2018