Own Goals are an unfortunate part of the game and especially more so for a defender.
Many of the times it happens is because the defender is under pressure from an attacker, yes occasionally it can be a mis-kick etc.
If you are going to count the OGs scored then to balance it up you need to count the number of "sitters" missed by an attacker (imho).
In the case of Craggs, frequently he is the only defender near the ball and also (again imho) the player most likely to put his body on the line to stop an attempt on goal.