This is the first time I see a boxer not having a trainer for himself, it's like playing a basketball being a playing coach. wow.. this is just unique, hope it will have an impressive result and he could beat the heavy favorites here.
Some trainers are hired and not really related to the boxers, while some are close friends and had been coaching the boxer since he started his career. But in Brook's case, his trainer simply declined due to the pandemic and the risk of going abroad
(clearly stated by Baofeng). Ingle also stated that,
He does his own thing. Like I say, he’s 34, he has three kids, he’s made his money. We’ve had a good run.
which simple indicates that whether Brook has Ingle's coaching and training or not, Brook knows his thing as Ingle trusts him that he can.
Basically, my judgement is that Brook can handle this fight very well. It is really an issue if a boxer has never been lost in a game, as it could indicate that he never had any frustration nor motivation to not lose at all. Also, having the change of coach wouldn't mean that the routine and the boxer's strength would change as well. Hence, this might be a close fight, but Brook has more chance.