Centre is the hardest defensive position because of the need to make decisions every time the ball comes your way. Thats probably why he's struggling, and may never get to the required standard. It could also be in part who plays alongside them - James Maloney causes his centres no end of grief by being a poor defender and making bad decisions himself. Not defending Handley particularly, but if he had good defensive partners inside and out it would make learning a lot easier.
Re Sutcliffe, isn't putting him in the second row just another attempt to find him a position? If we really want to kick on and he wants to play there (or anywhere settled for that matter), he ought to be DR to Fev and told to get experience and prove himself there first. We really can't afford to have supposedly experienced players learning on the job in the first team only to find out that they're actually not that good. He's been given a reasonable go at stand off, full back and centre without looking a standout anywhere. Apart from the fact he's contracted, I don't see how he's earned any more chances without proving himself first.