Ok, it is a matter about personal views on football, skills, movement, chemistry.
For me, Semedo always looks as if we play: 10 Barca players + Semedo.
He plays as if he doesn't belong to a team.
Zero chemistry, zero understanding, zero natural on and off the ball movement which fits to our team.
On the other hand, Roberto has ALL of that.
Now, if people will look only at KEY actions like: how many dribbles he made? How many crosses he made? How many runs did he make etc?
Then you won't see THAT much.
But to some extent, you know how some people say about Xavi (among midfielders) for example: he is always there, moving, making himself available, and even if he doesn't make too much in terms of assists, he made 100s of good things in build up, movement and attacking.
I am not saying that Roberto is Xavi, but he GETS IT.
He understands what our team is doing, what he is supposed to do, what he is supposed to do, where to move, when to move.
He is bad in defense sometimes, though.
On the other hand, Semedo is totally lost. A guy plays as if he doesn't understand anything what is happening around him.
And his attacking runs are more like: fuck it, I have no idea whether I should run or not in this moment. I will just run down the wing and hope that someone will pass the ball to me.
This analogy will be slightly exaggerated, but if you ever played some weird logical or Japanese videogames or games on Mobile phones?
Do you know that feeling when you don't read a guide, you just click: yes, yes, start, yes, yes, start.
And the game starts, and you have NO CLUE what is this game about. What are you supposed to do. You don't even know controls.
And then you randomly click buttons one by one and realize: oh, this button makes me run. Oh, with this button I am moving my player in this direction etc.
And then, if you would have a friend looking how you play (and if he knows how to play that game), he would probably look at you and laugh as fuck, like: loll what are you doing? Do you know what are you supposed to do at all, lol? This is so funny!
Well, at least for me, watching Semedo in attack (not in defense) feels equally as weird as playing a weird Japanese video game without reading instructions and a guide first.
Semedo for me is totally lost when he comes into an opponent's half.
Not only the end product, but everything: decisions, runs, on the ball movement, off the ball movement, passes, everything.
So, in short:
Roberto is not too skillful guy (as a RB), but he understands what this "video" game is about. What is he supposed to do, how to kill the enemies, run, jump, collect coins and similar.
Semedo, in terms of a video game, is a guy who on paper may be more skillful than Roberto, but he didn't bother to read instructions and he is just running aimlessly and clicking buttons for no apparent reason and without too much logic.
To some extent, this is why don't like Dembele either.
For example, yesterday, he had a few awesome solo actions, but other than that, with him I also have a feeling as if we have 10 Barca players and Dembele on a field.
And then when people say: Dembele and Semedo have an awesome connection on a field. Well, to some extent, that is because neither of them understand our movement, so they are playing in their own way and passing to eachother on the right flank
Anyway, Dembele currently doesn't understand our movement, but at least, he can offer magic in individual actions from time to time.
Semedo, on the other hand, doesn't get our movement and actions at all, and unlike Dembele, he can't offer absolutely nothing in solo actions with his end product.
Imo, no point in explaining this further.
If someone doesn't see how lost Semedo looks on a field, and how his chemistry, understanding with teammates and movement looks like, then there is really no point talking too much about Roberto vs Semedo in attack.
Roberto is meh to ok in attack.
Semedo is absolutely horrible and doing almost everything wrong in attack.