By all accounts (I'm on another continent) Plummer has been the best player on the park for us, in both games so far. So don't see why we need to sign another type of centre half just to try and help McAusland play better! So the day's of blaming Potter, Mair, McGregor, and Goodwin for McAusland's 'moments' are over. If he continues to put in performances as described, whilst Plummer strolls through games, no-one can blame his defensive partner.
If Plummer is as good as described, we should look to capitalise on his season with us, and get in an experienced centre half, ala Michael Duberry at St Johnstone, full of experience to play beside him.
McAusland can fill in off the bench where necessary. Because I really can see us progressing up the league when McAusland is a cast iron first pick, let alone Captain.