Mateo has been replaced by Sebastine Ikahihifo at back-row.
"I don't think he's been playing as well as he can so he needs to go back and work on some things with our NSW Cup side," McFadden said.
Chad Townsend has also been dropped in favour of Thomas Leuluai, but that was going to happen eventually. Leuluai was the Warriors' best player in the second half of last season and demands selection now he's over the groin injury that wrecked his World Cup.
"Thomas needs to be in our team. He's our leader and we have been building him up slowly. He's getting some conditioning in his body now and is ready to go."
McFadden knows he's on trial as the club consider their next move around a coach. The 36-year-old is highly rated and could be given the job permanently but there are others who have already been thrown into the mix.
Former Cowboys and current assistant Neil Henry has been linked with the job, as has St Helens and former Dragons coach Nathan Brown. Wigan coach Shaun Wane has long been talked about as the Warriors' next coach, something strenuously denied by management, and David Kidwell is also a consideration.
The biggest name to emerge is Tim Sheens, who lost out to Elliott after Brian McClennan was sacked at the end of 2012. His manager Wayne Beavis added to speculation when he told Sydney's Daily Telegraph: "I will certainly be putting his name forward if the Warriors are seeking candidates. Tim would be an ideal candidate and would bring experience and solidarity. He is the current Australian coach and a four-time premiership-winning coach."
Sheens is understood to be less than happy with his manager but his contract as Australia coach runs out at the end of this year.
McFadden made a handful of other changes to the side to face the Bulldogs. Ngani Laumape starts on the right wing in place of Glen Fisiiahi, who has a shoulder injury, and hooker Siliva Havili is poised to make his Warriors debut off the bench.
Utility Dominique Peyroux will also make his first NRL appearance of the year from the interchange bench and prop Charlie Gubb and back-rower David Bhana are included on an extended bench.
The biggest change needs to come in the players' attitude. They were dreadful in their three defeats this year and owe the fans a more committed performance.
"We have tried to put [the Sharks game] behind us," McFadden said.
"The players are certainly taking some responsibility for their performance last week and it starts this weekend."
The Bulldogs are in good form, having beaten the Roosters (9-8) and Storm (40-12) in their last two outings.
