In a difficult season for the Toffees, only Wayne Rooney scored more than Niasse's nine goals in all competitions. But apparent personality clashes and disagreements are causing major problems that is reportedly leading many to question their place at the club.
According to the The Sun, one unnamed senior player told a friend in relation to Niasse, "I say everyone chucks transfer requests in unless Oumar goes. He's the problem. He goes, problem goes."
Home grown teenage starlet Tom Davies has apparently considered quitting the club because he has 'had enough of all the sh*t' and is feeling 'down every day' as a result.
Niasse himself, who cost Everton £13.5m in January 2016 and has rarely been more than an outsider, is said to feel 'uncomfortable' at the club.
A source told the tabloid newspaper, "Senior players are threatening to leave. Everton is in crisis.
"A major reason behind the abject season has been the split dressing room. Clubs and teams always have ups and downs with big players and even bigger personalities. But this has been off the scale.
"Some players have been left depressed and feeling they don't want to continue. It has affected their playing performances. It has all got so out of hand and senior pros are furious. This hasn't helped the team's woeful season. Everton didn't used to be like this. Some stars want out."
Checked with a senior figure in #Everton's first team set-up about this bizarre story of Tom Davies and Oumar Niasse being at the centre of a dressing room crisis.— Greg O'Keeffe (@GregOK) May 24, 2018
The reply was short and sweet -
Phil Jagielka, Seamus Coleman, Jordan Pickford, Michael Keane, Dominic Calvert-Lewin, Mason Holgate and Jonjoe Kenny are all said to be involved in 'heated discussions'.
It is said that Wayne Rooney has tried to restore peace, but even he seems to have had enough of the drama, allegedly one of the reasons why with the former England captain is on the verge of joining DC United in Major League Soccer just one year after his Everton homecoming.
However, not all may be as reported as BBC and former Liverpool Echo journalist Greg O'Keeffe claims he has been told the story is 'All false' after checking with his own senior Everton source.