He's got the footwork and skills but lacks the vision and brain. I recommend everyone to (re)watch the CL final 2006 after Iniesta replaced Edmilson in the 2nd half and played as the deepest midfielder. He was about the same age as Rafinha is now. His throughballs and passes between the lines were ridiculous, completely changed the game, created Eto'o's goal as well. Night and day between young Iniesta and Rafinha.
He can become a decent player for sure but he lacks that special something to become a nailed on Barca starting midfielder IMO. He'll probably be in and out of the team for the next 2 seasons and then move on and have a decent career elsewhere like Motta after Barca buys someone like Pogba.
1-You are comparing him to Iniesta ,but the think is Xavi/Iniesta/Messi/Puyol are probably the greatest player in their position in the history of the club not just La Masia
If we are gonna put those as our reference in judging La Masia prospects it will be decades till we promote someone
2-You are putting Motta as a comparison to the level of player he might end up too ,that is a one I actually like but not for your reason
Motta was never a star in the making for us but he was very solid squad player for years and he showed that the academy can give us squad players and that is very important
Motta could have been playing for us till now ,the main reason he didn't was the injuries he had .it plagued him for several years and the club was a bit fed of it .he moved to Atletico and situation didn't get better then with Genoa he was healthy again ,same with early years with Inter
There is a lot of what could have been if Motta was healthy .Rafinha can be a very good player for us for years to come ,not just couple of seasons .and he doesn't have to be Iniesta for that ,just a good 3 option in the CM/AM combo