Putting aside the argument that this is an incredibly stupid time of the season to be playing a meaningless friendly, this is a well deserved call-up for Jack. He has been in excellent form for most of the season and most fans were surprised he wasn't named in the original squad.
The worry now is that one of Ross and Cuthbert gets injured in tomorrow's game at Broadwood. Ross has been struggling with an injury in recent weeks and his form has dipped, while Cuthbert is a vital part of the defence.
Good luck to the pair of them anyway - just come back in one piece please!