Ontong lamented the dropped chances in the field, saying Reeza Hendricks was put down early in his innings and made the Cobras pay for that costly error by scoring 157.
Pite van Biljon was bowled with a no-ball, and added another 80 to his total.
In the first game of the Sunfoil Series, the Cobras dropped Neil McKenzie early in his innings and the former national opener subsequently struck a ton and steered the Lions to 413 in their first innings.
They also grassed Dwaine Pretorius early in his innings and he recovered to record a half-century.
Ontong said the fact that some members of the bowling attack were side-lined due to injuries, did play a role in the sub-par performances in the first two games.
Beuran Hendricks bowled much better in the game against the Chevrolet Knights following his first game back against the Lions at Newlands, added Ontong.
“I just think as a team we need to put in better performances in every game.
“We also need to lift our intensity levels,” he said.
The Cobras will meet the Lions, marginally behind The Unlimited Titans on the Sunfoil Series log, from 8th January at Senwes Park in Potchefstroom.
The visitors will be bolstered by the return of Stiaan van Zyl, who scored a century on debut for South Africa at SuperSport Park in Centurion.