Bartra as a DEFENSIVE full back.
It's not like Dani brings much to the table outside of a mostly imaginary linkup with Messi, but having a solid defender on the right side would do wonders for us. Even on Bartra's penalty, a defensive RB would have solved that problem before it even manifested.
We are Barca.
In 80% of matches, our main concern is how to score Goals and break the defense and NOT how to have even stronger defense.
We are losing more points (and titles) with 0:0 draws against poor teams (where we couldn't score) than in matches when we lose 0:3 or 2:3 and where we needed a better defense.
So, with a more defensive minded RB after Alves, we will probably be overally weaker than today in terms of points over the whole Season.
In our team, a RB probably attacks and links up with attackers 75% of time, and defends 25% of time.
So, if Bartra is a better defender than Alves, that doesn't mean too much in 80% of matches where we control the game, attack all the time, and need to score 1-2-3 Goals.
Bartra on one flank, and a headless chicken Alba on the other side, doesn't sound like a too good recipe for winning more points than Real in La Liga.
That could be a good recipe in big matches.
But not against teams like Celta or Malaga at Camp nou, or against Elche, Granada and similar team in away games.