Hibernian's top scorer Leigh Griffiths has been recalled by Scotland boss Gordon Strachan, while the uncapped Stuart Armstrong, Gordon Greer, Ryan Jack, Gary Mackay-Steven and Tony Watt are also included.
Although the World Cup qualifier is meaningless in terms of progression for the already eliminated Scots, Matteo felt the Leeds striker's experience would have led to some involvement in Zagreb.
Matteo said: "I am surprised. I really like Ross. He's wholehearted, the fans love him, he's a good lad, he works hard for the team and he has goals in his locker. He can't half strike a ball.
"I'm surprised because I thought he would be Gordon's type of player with his work-rate and what he can bring. I'm disappointed for Ross.
"Obviously Gordon has brought a few new players into the squad. Greer has a cap at 32 which, on the back of the season he's had he deserves.
"But I'm gutted for Ross because he deserved that call-up. I thought he was a definite inclusion for Zagreb."