I made a comparison between CK and PM a few months ago (click me)

After 27 games:
PM: average rating: 9,0; 13 goals, 20 assists (14 CK)
CK: average rating: 8,0, 3 goal, 10 assists (7 CK)

My PM is gone at the beginning of this season, because he couldn't go with the teamquality and his performance dropped down.

My new PM doesn't assist (directly) that amount. He played 78 games and made only 13 direct assists, BUT his rating looks nice (average 8,9 at moment).
My old PM made at his last season 22 assists (47 appearances).

Maybe ibangali discovered something, my CK (kicked all from left side) made "only" 7 assists (29 games). I remember, 2 weren't from CK.
His stats: 158% passing, 166% crossing, 139% creativity and 35% finishing.
My (new) PM: 211% passing, 172% crossing, 167% creativity and 220% finishing.

So I don't think, finishing is important. Maybe they have a hidden SA, and if you train him the right one, it works better. Because the difference between old and new PM is really big.