Brent Read said on NRL 360 that Spencer Leniu is expected to sign a four-year contract with Parramatta.
The move appears likely to happen next season, although Leniu has another year remaining on his Roosters deal.
"I don't think this (the grand final win) changes anything," Read added.
"I think the deal is just about done. It's a long way down the path with Parramatta.
"It's a big signing for Parra. They need him."
Leniu told journalists after the grand final that he was leaving discussions about his future to his manager.
Code Sports footage later showed him embracing Roosters front-row teammate Naufahu Whyte.
"I love ya bro, thanks for everything," Whyte could be heard saying to Leniu, according to the publication.
The four-time premiership winner delivered a strong final performance in Roosters colours, running for 92 metres and breaking four tackles as he shifted the grand final's momentum.