Think Davies and Yedlin have to be considered exceptions in that list due to their age - they might be depth at present but they've been bought to be 1st choice in a couple of years (not necessarily saying they will be)
You're right of course. I also don't dislike any of the players mentioned. If I was the manager I'd probably bring in Stambouli and Fazio next game over Kaboul and Capoue. It's more of a process over results thing. Buying depth isn't as important when we have this much young quality especially with our dearth of top end talent that could be bought with the additional money.