I don't think it's that, I very much understand the way Pep want's to play and the technical aspects required, I just think Sagna is technically able enough whilst maintaining a high standard of defending.
If we were playing Barcelona, Spurs, Liverpool or Arsenal tomorrow, and our right back was up against Neymar, Lamela, Mane or Sanchez, I'd sleep much easier knowing Sagna was starting. I know this is just about the defensive aspect but like I say, technically, I don't think Sagna is that bad.
Nothing against Zaba, as he has been brilliant over the years but the last 18months haven't quite been right. Maybe Pep can get more out of him with a decent run of games, I guess we'll see.