Andy Ruiz Jr a one-hit wonder? A new trainer is a new start but can he commit fully?

Boxing trainers are often the last to get any credit, and the first to take the blame. If you want loyalty, so they say, buy a dog.

Andy Ruiz Jr begins the new decade by searching for a new trainer, coming off a rollercoaster 2019 when he shocked Anthony Joshua then admitted that "partying" and being "overweight" cost him the rematch.

Manny Robles, the man in the corner for the most major boxing upset in memory, has been harshly dealt with although he saw it coming when Ruiz Jr went AWOL. They hadn't spoken since December 7 at the post-fight press conference in Saudi Arabia when Robles sat visibly angry, and Ruiz Jr sheepishly apologised for his lazy preparation.

Ruiz Jr's loyalty has been questioned alongside his dedication and his weight, but changing trainers is hardly a radical move. Ruiz Jr has been here before, and it brought about the most successful year of his life.

His ruthlessness in getting rid of trainers and hiring somebody fresh has contributed to making him Mexico's first world heavyweight champion.

Jeff Grmoja led Ruiz Jr until his first world title fight, against Joseph Parker in 2016, but was replaced for the biggest moment of the heavyweight's career by Abel Sanchez, best known for training Gennadiy Golovkin.

Ruiz Jr lost to Parker, his relationship with trainer Sanchez lasting just one fight.

"A lot of people don't know the training camp that we had against Joseph Parker," Ruiz Jr sighed regretfully to Sky Sports. He wasted no time in replacing Sanchez with Robles.

No trainer has been able to stop Ruiz Jr's weight fluctuating - he beat Joshua in June after weighing in at a massive 19st 2lbs but added over a stone in the unsuccessful rematch.

Robles told Sky Sports earlier this month before their split was confirmed: "My job is not to call him every day. He's a man, not a kid, and must be treated as such.

"You can't convince someone to want something.

"The fame and money has been overwhelming for Andy. He's got to know how to handle it. Maybe after this defeat, the game has humbled him.

"Stay humble or be humbled.

"The first three months after beating Joshua on June 1, I had very little communication with him."

Robles was keen to add: "He is an incredible fighter and has proved that to the world. He is a fighter to be reckoned with - very durable with great skills but he's got to be ready."

"You can't convince someone to want something."

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Maybe a new man giving him orders will get Ruiz Jr ready.

Tyson Fury has made a similar move by replacing trainer Ben Davison, who led him through his comeback from a near-three year hiatus and through his first fight with Deontay Wilder, with Sugarhill Steward.

Interestingly Joshua, who steadfastly backed his own trainer Rob McCracken after losing to Ruiz Jr and was vindicated in the rematch, has backed Fury's decision.

"As a fighter, first and foremost, it doesn't matter about anyone else," Joshua told Sky Sports.

"If Fury feels like this is right for him, he has to trust his instinct and follow it because it will only be him that [gets in the ring].

"Tyson Fury has to do what's right for Tyson Fury because it's only his name that is mentioned when announced as the winner or the loser."

2020 can be a big year for Ruiz Jr. There is intrigue to discover if he is a one-hit wonder or not. Remember, he remains the only man to beat Joshua.

Promoter Eddie Hearn wants to pit Ruiz Jr against Dillian Whyte, saying: "That fight has more chance of happening in America."

His choice of new trainer will be crucial. But it is Ruiz Jr's decision, and his alone, as to how he approaches this new dawn.