So the stars aligned, and the importance of his move was underlined in the 19-6 win over the Titans on Saturday.
Fonua-Blake was a dominant, destructive presence, making almost 200 metres from 19 carries. That tally included an impressive 94 post-contact metres and the 1.89m, 118kg powerhouse gave the Warriors momentum whenever they needed it, creating a platform for the pack, who shaded their highly-rated opposites.
It's only one match, but it was an illustration of what he can do, and what the Warriors have missed over the last decade. They've had some good forwards, some very good, but often lacked a true enforcer.
It's partly because they have chosen to spend their money elsewhere – Sam Tomkins was a classic example – and also due to those types of players not being available.
But it's been an ongoing issue; the template is there, with the powerful props at the Storm, Roosters, Souths and Canberra, while the Cowboys' 2015 success was built around Matt Scott and Jason Taumalolo, but the Warriors have often had an underpowered forward pack.
That might change in 2021, with the presence of Fonua-Blake, and fellow Tongan Ben Murdoch-Masila, complemented by Tohu Harris, Leeson Ah Mau and others.
"He's a world class player isn't he," reflected Brown after Saturday's match. "As I [have] said before, we were fortunate to get Addin.
"Recruitment is the key to any successful club; if you don't recruit well, you don't do well. Being able to get a player of Addin's skill and talent for us was very important. He plays an important position, he is a very important player for our club now, as he was for Manly."
And as Brown pointed out, Fonua-Blake has arrived at an opportune time.
"He's only 25, so his best years are coming," said Brown. "He certainly is a talent. I still remember getting a call from [recruitment manager] Peter O'Sullivan saying we are a chance of getting this bloke – I didn't really believe it and nearly fell off [my] chair, because they don't come along every day."
So far, so good for Fonua-Blake. Teammates have been impressed with his willingness to take a leadership role in the squad and he has coped with the expectation of being one of the club's highest earners.
Brown was pleased with the "gritty" effort in sweltering conditions on Saturday. The Warriors defended for long periods in their own territory and lost two players to head knocks early in the second half. Their resolve was impressive, while the halves made good decisions when it counted.
"The NRL is a tough business," said Brown. "If you want to be successful as a club, you've got to work hard. Getting that sort of work ethic and the commitment from the boys is important and Saturday was round one. It's about doing it for 26 rounds, that's the challenge."