Michael Maguire claims inconsistencies in the NRL's crackdown are helping decide games, while also questioning how high shots can draw the same penalties as professional fouls.
The Wests Tigers were blown out of the water in a five-minute period by Parramatta on Sunday, as Mitchell Moses set up three tries with Shawn Blore off the field.
Blore was sent to the bin for pulling back on Parramatta hooker Joey Lussick's shoulders as Dylan Brown broke into free space.
Infuriating Maguire further was that 10 minutes later Maika Sivo was sin-binned and not sent off for a high shot that left Adam Doueihi concussed and still dazed after the match.
"Blorey put his hand on Lussick but I don't think it had any impact on the situation of what happened," the Tigers coach said.
"To have a bloke (sin-binned) like that. There is no foul play, it's a bloke touching a shoulder.
"We lost a player for 10 minutes for whole heap, but we are having players have to come off (injured) for high tackles.
"Is that (only) worth 10? What's the difference between both?"
Sivo's hit on Doueihi made him one of six players put on report in the match, while Parramatta second-rower Isiahh Papali'i was also sin-binned for dropping his knee on Luciano Leilua.
Maguire claimed the NRL was still yet to find consistency on on-field punishments for foul play, between putting players on report, sin-binning them and sending them off.
"It's affecting games. I know that," Maguire said.
"It's playing a big part. You're losing players and you need to adjust to what is going on.
"But they're going to need to find it fast, because it is costing games."
His comments came after Brisbane forward Kobe Hetherington was sent off on Saturday night after Corey Harawira-Naera fell into his shoulder in a tackle.
Hetherington was only hit with a grade-one charge on Sunday, with the match review committee deeming the tackle not as bad as one from Kevin Proctor on the same afternoon.
In Proctor's instance, he was allowed to stay on the field for his grade-two hit, and only placed on report in Gold Coast's loss to Sydney Roosters.
Parramatta coach Brad Arthur argued the Sivo shot was sin-bin sufficient and not a send off, but also claimed there is little clarity on on-field punishments.
"There has been a change of direction, so now you don't know what's going to happen.
"My concern is the things we've got to get right in our game.
"The game is going to have times when there are 12 players on the field and we've got a specific plan about what we're going to do.
"And we're not executing it, that's what annoys me."
Australian Associated Press