But now that a Super League move is sorted, Cook's focus is on igniting the last-placed Dragons, starting with his 250th NRL game at Magic Round.
Cook had been confident of a one-year extension during the pre-season, only for the Dragons to pause all contract discussions in April amid their form slump.
"I was days, maybe a week away, from re-signing here," the hooker said.
Soon after the contract freeze, Shane Flanagan stepped down as coach with the Dragons on an 11-game losing streak, a slide that now spans 13 defeats.
By the time the dust had settled on Flanagan's departure, the Dragons had told 34-year-old Cook they needed to prioritise younger players at hooker for next year and beyond.
"We asked a few times and sort of got the same response, so I had to let my manager know that we were going to have to look elsewhere," he said.
Cook still felt he had more to give to his junior club the Dragons, who handed him his NRL debut prior to stints with Canterbury and South Sydney.
He found it hard to be told he was unwanted.
"When you feel like you give so much to them, when those sorts of things happen, it can hurt a bit," Cook said.
"I definitely respected the business side of the thing, but obviously because I was involved in it, emotionally invested in it, there were definitely a tough couple of weeks where I was filthy at the decision.Â
"I obviously wanted to stay, you'd love to stay here."
The time in limbo was short-lived, though.
Former Dragons assistant and interim coach Ryan Carr reached out with an offer for Cook to join his Super League side Castleford on a two-year deal.
"The best thing is that I've made a decision now and I get to really enjoy this last year with the Dragons," Cook said.
"In saying that, I'm very excited to get over there as well."
Early in his career, Cook never thought he'd make it out of double figures for NRL games, much less bring up 250 as he will against Penrith on Sunday.
Cook managed only two games in each of the 2013 and 2014 seasons, and was preparing to spend all of 2015 playing NSW Cup at the Bulldogs.
"I just thought, 'Maybe this is it'. We had a really good NSW Cup side, maybe this is as far as I go," he said.
But a leg injury to Michael Lichaa gave Cook both a run of NRL games at the Bulldogs, and a chance to catch the eye of then-Souths coach Michael Maguire.
Three years later, he was the incumbent NSW No.9 and the Dally M Hooker of the Year for 2018.
A 250th NRL appearance shapes as another career highlight.
"It probably makes it a bit more important for myself, that milestone, not being at the club next year," Cook said.
"For it to be our first win of the year would be absolutely perfect. I'll continue to work hard here and hopefully we can get the job done."
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