and you have the decency to call yourself "fans".
Nothing wrong with criticizing Roberto, not at all.
Roberto is a great role model to La Masia players, especially in his case how far he has come since 2013 as he was close to leaving the club after not getting the game time and not impressing enough. Lucho gave him a chance and he worked hard and found a spot on the team.
But despite all that he shouldn't be immune to criticism either even if he's a local boy who came through the ranks. Despite the hard work and how far he improved, that really isn't enough to be a starting player for a club like ours.
RB is his best position but he has flaws that I doubt will be ever fixed and some that just can't be fixed as in pace and better technical ability with the ball at his feet. He's not "Slow" Like Rakitic, Pique etc slow but he really lacks that explosiveness that is crucial to most Fullbacks these days on both ends of the field.
Alves lost his pace but made up for it with intelligence and pure technical ability. Roberto has some good technical ability and while he isn't Brainless either He's actually pretty smart, it's not enough to make up for some of his major flaws.
When it comes to his defending, you can write pretty much an essay on just how limited he can be there. It's not due to a lack of effort though, you can clearly see how hard is trying but it's just not working for him.
I theorize that he can be good in a system like in a 3-4-3/3-5-2 as an RWB, and having a defensive RCB in the back three and a good workhorse Midfielder to help protect him and cover up for some of his defensive flaws like Conte's Chelsea. But we don't have a system like that and he has a Slow Rakitic and an out of form/Declining Pique trying to cover for him going forward.