Barker has probably played 20 minutes of football at the end of the games, and more than that he was played on the wing when he's a striker. I don't care how he played (I thought he made a couple of decent runs), that is not enough to make any kind of judgement.
I also don't think we need automatically to replace the people we've lost. LB was the obvious one that's been filled already and CB was another obvious move. From the rotations in the friendlies it looks like we're reaching down into the DS to look for replacements rather than automatically...