It is understood that Pastrana has been stood down as a result of his performance and will not officiate at the Crusaders v Hurricanes match in Christchurch on Friday.
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The Blues were the beneficiaries of several controversial decisions themselves, most notably when George Moala's try was awarded when it appeared to be a double movement, and when Cheetahs flanker Boom Prinsloo was sinbinned. The Moala try was the most contentious, Pastrana over-ruling his TMO.
Kirwan said referees weren't to blame for his side's up-and-down form this season, but he was keen to put scrums on the agenda because they were taking away from how the game should be played.
Last year was the first in which scrums were altered to fold in, rather than collide, to prevent collapses. This year, referees give a silent signal to the halfback putting the ball in, after complaints that an audible command gave too much advantage to the opposing pack.
But Kirwan said even that was too much. "The biggest problem with the game is that we're letting the ref decide when the ball goes in. That's what needs to change and if we change that then the game changes."
Kirwan said that before the season started, the New Zealand coaches asked Sanzar to allow halfbacks to put the ball in without the ref's command but that had gone unheeded.
Scrums now have become so contested it is almost a disadvantage to be awarded one. Even allowing for the referee's silent command, the opposition pack has an automatic one-man advantage because their hooker is not striking for the ball.
A cue and put-in by a halfback could swing the advantage back and allow backlines to once more launch attacks off what would be a much more stable platform.
"Our forwards need to know when the ball is coming in, and if the opposition is good enough they can try to push us off it," Kirwan said.
"There's too much technical stuff for the ref to decide. It's a difficult thing to referee but we can't launch from scrums any more."
While Kirwan said there was much to work on before this Saturday's home match against the Highlanders, a bonus-point victory after travelling back from South Africa was extremely valuable.
The Blues' next four games