Flanagan admitted he was "shocked and disappointed" at his Roosters exit on Monday night, departing the club with a year still to run on his contract.

Halves partner Keary himself went through a similar situation himself.

Both he and Clive Churchill Medallist Ryan Papenhuyzen went to Oakhill College together and were rejected by Parramatta, told by the Eels they were too small.

Keary has since gone on to win three premierships at South Sydney and the Roosters, while Papenhuyzen will join him in NSW State of Origin camp on Wednesday night.

"Yeah (I think it can be the making of him). It happens to a lot of players," Keary said.

"You move clubs early in your career. It happened to myself. And then you just deal with it and keep playing and move on.

"He's a good kid. I think everyone sees maturity from afar. He's very calm and cool headed. Very mature for his age. He'll bounce back."

Flanagan's exit from the Roosters comes after he was signed as Cooper Cronk's replacement, only to be dropped mid-season.

He found his way back into the side through injuries before the finals, until they exited after losses to the Panthers and Canberra.

The 22-year-old becomes Trent Barrett's biggest-name signing at the Bulldogs, with the lure of working with the former Manly coach the likely biggest appeal.

Barrett is seen as one of the best attacking coaches in the game, having helped restructure Penrith's attack and change the way Nathan Cleary played in 2020.

It helped the Panthers go all the way to the grand final on the back of 17 straight wins before their 26-20 loss to Melbourne in the decider on Sunday.

Daly Cherry-Evans also played an exciting up-tempo style in his time under Barrett at Manly between 2015 and 2017, as he took full control of the Sea Eagles' attack.

A similar chance now awaits Flanagan.

Several questions remain around the rest of the Bulldogs' spine, after Canterbury chopped and changed in key positions this season.

They have also signed Nick Cotric, Jack Hetherington, Corey Waddell and the injured Blake Green.

Meanwhile forward Poasa Faamausili was also released by the Roosters on Tuesday, allowed to sign a two-year deal with St George Illawarra.

Keary will likely partner Lachlan Lam in the halves at the tricolours next year, unless Trent Robinson goes to the market for a more experienced option.

Drew Hutchison and up-and-coming star Sam Walker are the other alternatives.

Australian Associated Press