There was a serious shortage of defenders all season long. McCormack played at RB and even CB at times. Keohane and Beattie also played RB until Beattie claimed the position. A couple of youngsters also got games. Delaney has been a revelation but he was very raw for the first few games. Nobody knew how many games Benno could play. The back four changed so many times that it's a miracle we conceded the least goals. Perhaps surprisingly for an ex-striker, Caulfield knows how to make a team difficult to score against.
There is great respect at the club for Dunleavy so I'd expect him to stay on if things look ok on the injury front. And there's a whole pre-season to get in defensive cover. Most fans are more worried about the attacking shortfall tbh.