He's conceded 30 goals in 14 games for AZ
edit: for reference their other GK conceded 38 goals in 32 games before Krul signed
How many of those 30 were his fault?
For reference the Dutch League is typically the highest scoring league in Europe.
no idea, not many are solely a GK's fault anyway. Depends how many he could/should have saved, again something I don't have an answer for. When you don't know things like that, the stats are all there is to go off
..and that may be, don't see what relevance that has to him still having a worse goals conceded per game ratio to the other, younger GK, in the same league & team