Is Soldado injured?
They know it but there are only so many people you can buy. Spurs have effectively replaced the back four but it will take a few weeks to get them all fit and playing together. Davies, Vert, Fazio, Dier, with the american fullback coming in next season. Not sure why Davies isn't getting games though, he was good last season, bad preseason or injury? I can't imagine Rose looking better than him in training because the guy doesn't know how to defend.
Vert and Kaboul will be the central two I think, with Fazio/Dier as back up. I think Poch is trying to be meritocratic; Davies is not as adventurous as Rose.
You would have thought that was a positive for a game against Liverpool though
Edit- this may be something that Poch will need to learn. I remember reading how Southampton only focused on their own game and didnt make any plans for the opposition during the week. Liverpool have got to be one of the most compelling arguments against this method.