He is just coming back from a very long term injury, so I'm not sweating his performance. I wouldn't expect much from him until next season, tbh. Although I have to wonder, why would Lucho start him and Arda in midfield? It's like he just wanted to lose.
Thiago isn't even that good for Barca system as people here love to think. Rafinha has what it takes to be a Barca squad player but not necessarily a startup player.
He's good enough now to be a squad player now and has potential to be our starting MF in two years. What's most important is that Lucho believes in him and we've all seen what that kind of confidence (and I think Lucho likes Rafinha even more than Roberto) did for Roberto's development this season. He just need time to get back into playing rhythm and form and it probably won't happen until next season but then watch out for him.