World Cup winning All Black Thorn was making his Leinster debut in the second row alongside club captain Cullen, who was appearing for the first time since New Year's Day following Achilles surgery.
And while Richard Hibbard's late try for the Ospreys brought Leinster's 20-match unbeaten run to an end and trimmed their lead at the top of the RaboDirect PRO12 table to eight points, Schmidt was impressed with all three performances.
"Leo Cullen is just a great solider. He was half a lung short in the last 20 minutes but he really soldiered on. He showed a cool head and you can't fault the decisions he made," said Schmidt.
"Brad put in a great performance. He's still fitting into our system. He was slightly out of kilter but he made his presence felt on a couple of occasions as well.
"Brian looked very sharp for a guy who hasn't played as long. And as time goes on, he'll be able to put in an 80 minutes for sure."
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