"I'm sure Robert will be a big player for us this year," Mowbray told the Birmingham Daily Mail.
"It's been a bit stop-start for him because of the eye injury he picked up in pre-season, but he'd played very well for us in pre-season and had looked very influential.
"He's been a miss over the last six weeks, but he's got back up and running with his country during the international break, which has been a plus for us.
"I think he has the right mentality to play in England. He relishes the physical side of it and technically he's very good."
Koren will be hoping his goal against the Robins will be enough to keep his place in the staring XI to face the Iron, but Mowbray has adopted a rotation policy so far this season.
Midfielders Chris Brunt and James Morrison are both likely to be recalled to action.
The Baggies' only absentee is Roman Bednar, who is still building up his fitness.