The CB trio does not look good in possession IMO. In the past 2 games alone, we've given the ball away countless times trying to play it out from the goal keeper. No doubt fatigue compounds that, but we simply do not move the ball out and around fast enough or competently enough. And I'm not just saying this based on a few friendlies. Spalletti implemented this idea, and we've vastly improved since Mancini days, but we're still simply not good enough in this regard. The CB's and midfielders need more time to function as a unit and become familiar with the channels / patterns / movements etc to reduce the amount of turnovers in our own final third.
One of the issues I've had with de Vrij for over a year now is that he takes the back pass option too often, even when there's very little pressure on him. As I've just said, I think we aren't comfortable enough playing the ball out from the back. And de Vrij repeatedly passing backwards to Handanovic (as opposed to literally anyone else) just puts us in that difficult position every time. In the time he's been here, there have been countless times when he's had several options to pass forwards or sideways, or even just hold the ball, but he inexplicably and unnecessarily passes to Handanovic. It should be the last option, but de Vrij chooses it way too often.
Side note: I personally think Skriniar looks very uncomfortable playing as the wide CB. In that position, he's more regularly being attacked by players looking to take the ball out wide. Most of his godly 1v1 stops against difficult forwards like Mertens, were in a situation where they were looking to take the ball inwards, towards goal. It's a system issue, more than one of personnel, but Skriniar excels at closing down the space for a player to attack then cleanly taking the ball off them 1v1. When players do have the space (and pace) to exploit out wide, I feel that Skriniar is in a position where he's not able to do what he's best at.