It was August 2016 and the player in question was Oumar Niasse, signed by Koeman’s predecessor Roberto Martinez six months before.
This brutal quote came barely weeks after Koeman took over and the Dutchman didn’t want a piece of the Senegalese striker.
Don’t worry if you don’t know the name. Niasse is unlikely to have registered on your radar – he’s played a grand total of six league games for Everton in almost two years.
But at the time of his signing, he was only behind Marouane Fellaini and Romelu Lukaku on the list of Everton’s most expensive players.
So how did the Merseyside club spend an eye-watering A$23 million on his services, yet quickly deem him not even good enough for the first team?
The truth is that we will probably never find out everything that went down.
A desperate January transfer window signing from Lokomotiv Moscow, Niasse arrived at Everton out of shape and carrying some sort of mystery injury.
He didn’t play until April 30 and his first performance against Bournemouth was – putting it kindly – an absolute shocker.
Nobody could figure out how he’d been recently named as the Russian Premier League player of the season.
“Still early days but Oumar Niasse has touched the ball only once – briefly – and is looking a little lost,” tweeted the Liverpool Echo’s David Prentice. “Blues effectively got 10-men.”
“Whoever at Everton decided Oumar Niasse was worth £13.5 million should be under investigation for cooking the books,” added journalist Richard Buxton. “An Ali Dia performance today.”
If that was coming from the press box, you can imagine what the fans were saying. They went for him – and for those responsible for signing him.
Martinez didn’t make it to the end of the season and Everton spent the next few months desperately trying to offload the striker.
But with his bulky wages (said to be $93,000 per week), nobody was prepared to take him on.
Koeman pressured Niasse into leaving: denying him a squad number, preventing him from training with the first team and even removing his locker.
Yet Niasse kept turning up to training, so they dumped with the under-23 team: the ultimate insult. But the demotion only made him work harder.
He never missed a session and took to his task with the youngsters, scoring with a surprising frequency – topped by a hat-trick in a 6-3 win over Reading.
Even under-23 coach David Unsworth admitted the striker deserved “massive praise” and that he “had been great with this group of players - both in training and in games.”
But Koeman was unmoved.
Only Hull City were prepared to take a risk on Niasse – a result of their desperate bid to avert relegation led to a loan deal being struck in January.
Eventually, Niasse broke into the first team and although he couldn’t prevent the team being relegated, he scored five goals in 19 games, including on his starting debut in the League Cup semi-final second leg against Manchester United.
Hull were given a $17 million option to buy Niasse and had they not been relegated, one suspects they would have taken it up.
He trudged back to Everton, where Koeman, for the umpteenth time, let him know he wasn’t wanted.
After undergoing a medical on deadline day last month, an $11.8m move to Crystal Palace collapsed (reportedly) because of the demands of the player’s agent.
A loan deal to Fenerbahce also fell through. And so the nightmare rolled on.
Stuck in no man’s land, Niasse just trained and trained.
Word spread about his work ethic and determination to prove himself.
Everton fans appreciated that he never bad-mouthed the club and many began to argue that he deserved another go.
Eventually, on September 8, Koeman allowed him back into first-team training.
“Sometimes in life you need to give some opportunities,” he admitted, probably through gritted teeth.
Finally, Niasse was finally allowed to sit on the bench in League Cup game against Sunderland last Wednesday.
Just 18 minutes after coming on, he smacked home a superb shot from the edge of the box to seal a 3-0 victory. He was given a roaring reception for his efforts.
Seventy two hours later in the Premier League, Everton were in a real bind against Bournemouth, the same team he made that shocking debut against 18 months before.
Trailing 1-0 and with Wayne Rooney injured, Koeman threw Niasse and teenager Tom Davies intro the fray. An act of desperation.
But Niasse’s desperation was even greater. Not long after coming on, he won the ball in midfield, then linked up with Davies before belting home a superb effort.
With the Goodison Park crowd urging him on, and with Toffees suddenly alive, it was that same duo who combined for Niasse’s second, beating off two defenders to head home a winner, sparking scenes of delirium as Everton pulled themselves out of the drop zone.
“Oumar was incredible,” Koeman said after the match. “Nobody can stop him at the moment. He did well and all credit to the player.”
Early days they may be, but this nightmare is finally showing signs of a happy ending, for club, coach and player alike.