Jared Payne's red card against Sarries has changed the landscape of rugby - Joe Schmidt
Mr Schmidt was speaking at an event at NUI, Galway where he warned that the decision would now force coaches to change the advice they give to their players.
"I feel he was unjustly red-carded by the referee. I think that was a massive blow for Ulster at the time. But it has changed the landscape and one of the things I would have said to anyone chasing the ball is it's just you and the ball," he said.
"If you're chasing the ball and it's coming down. You are trying to judge the speed of descent of the ball and trying to judge how far you need to go to get to it...You don't do that by looking around at whose there. You do that by fully committing to the ball and judging the speed of the ball. The landscape has changed just a fraction," he warned.
Mr Schmidt questioned what advice coaches could now give their players in the wake of the decision.
"They've said now it's the responsibility of the player on the ground to make sure they don't bang into anybody who has gone up in the air. What do I do now? Do I just say it's you and the ball, there's a risk in that because I might get a guy red-carded. Is that good coaching?"
"Those are the challenges. It's a very small thing but very small things win very big test matches," he added.
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