Two defeats and the two broken eye sockets he suffered in those fights left the hitherto unbeatable Brook feeling old and vulnerable.
In boxing, successive defeats weigh heavy on a fighter, irrespective of the 36 victories and the numerous titles that had gone before.
Fast-forward a year, however, and the 32-year-old ‘Special One’ from Sheffield is feeling ‘born again’ and ready to continue fighting for many more years to come.
He puts this regeneration down to ‘a change’; with a new trainer in John Fewkes in the absence of his old mentor Dominic Ingle being the obvious shift.
A settled family life has also contributed, meaning Brook steps into the ring tonight against Michael Zerafa in a WBA super welterweight eliminator in Sheffield, feeling like he did 14 years ago when he began his professional journey.
“A change is always good, it’s freshened me right up,” said Brook, who is making his second appearance at super welterweight after beating Sergey Rabchenko in his comeback fight in March.
“That change has got me really excited and set a fire in my belly. It’s a change that has revived me.
“I’ve changed trainer, I’ve got a new outlook, I’ve got control of my own life.
“I don’t just believe that I’ve got a year left any more, I really believe I’ve got a few fights left in me.”
That is unlikely now to be Amir Khan, with the ‘will-they, won’t-they’ saga the two have contributed to set to fizzle out with Khan taking a fight with Terence Crawford in America next year.
Promoting tonight’s Sheffield Arena bill at Bramall Lane on Thursday, Brook was keen to move away from talk of Khan and plot his own course back to the top. “I’m going to fight the top dogs instead,” said Brook, who could seek a rematch with Shawn Porter, the man he won the IBF world welterweight title off, or with Errol Spence Jnr, the man he lost it to.
“Khan keeps saying this fight will always be there, but it won’t. I want to become world champion again. Look at all the other names that want to fight the best, he doesn’t want to fight me.
“There’s some big fights for me in America, from welterwight to light middleweight I’m hunting those top boys.
“That’s the direction I’m heading in 2019. I’ve got some big exciting performances ahead of me and I’ve still got lots to give.”
The split from his long-time trainer Ingle is an amicable one, says Brook, and owes more to timing and the trainer’s family commitments than anything else.
But once Ingle became unavailable, Brook moved swiftly to hire an old amateur opponent and experienced Sheffield professional in Fewkes. “We’ve been friends for a long time and I knew automatically when I changed trainers John would be the man for me,” said Brook.
“Kell Brook can fight at the top for another three or four years,” responded Fewkes.
Zerafa will cause problems tonight. The Australian has lost just twice in a 27-fight career and is six years younger than Brook, who has been an unfancied challenger before himself.
“He brings a big heart,” said Brook. “He knows if he beats me he’s onto the big guys as well. This is a world title fight for him.
“I’ve been there before against Shawn Porter, I know the feeling when that fire burns inside.”
A tasty undercard includes a fourth professional fight for Leeds’s Rio Olympian Qais Ashfaq, who is stepping up the standard of opponent with Jay Carney the first fighter he has faced in the pro ranks who has won more than he has lost. “I’m starting to find my feet now in the pro game,” said Ashfaq.
Sheffield’s unbeaten featherweight Kid Galahad fights Brayan Mairena with half an eye on the fight two weeks from now when fellow Yorkshireman Josh Warrington defends his IBF welterweight against Carl Frampton. Galahad hopes to meet the winner in early 2019.
But all eyes tonight will be on Brook. If he gets his wish, then the big fights in America are on the horizon, meaning this could be his 14th and final fight in his home city.
“It could be an emotional one, you might see a few tears,” admitted Brook.