Eels coach Brad Arthur still "half blames" his new star front-rower Reagan Campbell-Gillard for setting in motion the worst season of his career.

Ex-Panther Campbell-Gillard has a new lease on life in blue and gold after being released by Penrith last season without even beginning the long-term extension he signed in 2018, understood to have been worth more than $4 million over five years.

Penrith are still partly paying the contract for Campbell-Gillard and fellow Panthers junior Waqa Blake to play against them in this week's table-topping Battle of the West.

NRL.com understands Penrith are paying a significant portion of Campbell-Gillard's salary for 2020 and also wearing a far smaller amount for Blake to line up out wide, Parramatta picking up his four-year Panthers deal last June as Ivan Cleary overhauled his roster.

Arthur says he has always rated the former Penrith pair.

Begrudgingly so when they engineered a memorable round one revival two years ago, the Panthers running in 24 unanswered points as Parramatta's 2018 campaign went to water after a little more than 30 minutes.

Reagan Campbell-Gillard torched Parramatta in 2018. ©NRL Photos

"I've always been a fan of Reg," Arthur told NRL.com ahead of Friday's mouth-watering derby.

"I remember in 2018, I still half blame him for setting us on the wrong foot for that season.

"We were pumped and going really well when we were out there at [Panthers Stadium], I think we were leading 14-0 and they scored just before half-time.

"It was Waqa Blake who scored. And I'd always been a fan of his too.

Match Highlights: Panthers v Eels - Round 1; 2018

"Then the Panthers came out to start the second half with Reg charging at a million miles an hour from the kick-off and I thought he changed the whole tempo of the game.

"We lost, then lost six in a row afterwards and ended up with the wooden spoon."

Campbell-Gillard has been blunt in appraising his 2019 form and Panthers exit more than once since shifting clubs.

He came off the bench in 20 of his 23 games last year and "felt like I enjoyed football again" when he was dropped to NSW Cup.

But there's "definitely no point to prove," he said.

"They've moved on I've moved on. They've got players to fill the spot there so no point to prove."

Campbell-Gillard has unstoppable since the COVID-19 shutdown, running for more than 200 metres each week in the NRL's new high-octane six-again format.

The 26-year-old dropped the best part of eight kilos over the off-season doing extras "every single morning at 5.30am" alongside front-row partner Junior Paulo, according to Arthur.

The one-time NSW Origin prop kept the weight off throughout April and May, and credits Arthur's coaching for his dramatic turnaround.

"The coaching staff, it's chalk and cheese to what I've been under last year," Campbell-Gillard said.

Match Highlights: Eels v Sea Eagles

"I'm not stirring the pot with anything. Ivan has his way that he coaches and Brad has another way.

"I personally feel really comfortable with how Brad wants to coach and having that sense of being wanted to be in a team.

"Brad is a coach that I can really get along with. But I've had some really good coaches in the past and Ivan's been a really good coach as well. He gave me my debut back in 2015.

"I've got nothing but thankyous.

"It's nothing negative or trying to attack him personally as a coach. But personally as a player I needed to get out of there."