Celtic easily dispose of St Mirren
Paddy McCourt beat five players before smacking a shot past Paul Gallacher.
Shaun Maloney curled a shot home in 78 minutes to seal the three points.
Despite the routine nature of the win, Mowbray was felt his players had fallen below the standards he demands.
"It was a very disappointing performance and it was way, way below what we expect as a team," Mowbray told ESPN.
"It was unacceptable for our supporters. There were positives in that we got a clean sheet but the standards have got to be higher.
"There has to be better decision making, better passing, better movement and we must be more clinical. I think we can be better everywhere."