Niasse was demoted to the under-23s, had his personal locker revoked and was off to Hull City on loan in January 2017.
Despite impressing with four Premier League goals, Koeman still overlooked him upon his return, omitting the Senegalese striker from his pre-season preparations for last term, and only handing him an opportunity after injuries forced his hand.
Niasse proved the Dutchman and his critics wrong, scoring three goals in his first two appearances of the campaign and handing Koeman a lifeline at the time.
The former Akhisar Belediyespor man ended the season with nine goals and two assists in 10 starts across all competitions - a return only bettered by Wayne Rooney, and he believes adequate preparations ahead of 2018-19 can unleash his prolific form.
“As a professional I fight to be ready every time. If I have a pre-season then I know I can do much better than I did last season,” Niasse told evertonfc.com.
“Next season I want to be ready from the beginning. The goal at West Ham was my eighth in the 10 Premier League games I started.
“Whenever I get a chance, when I play a number of games in a row and have a pre-season, people will see, as a striker, I know how to score goals. It is on me to do that when I play in the team."
Niasse has two more years on his current contract, and he has the opportunity to prove his worth in the next two campaigns.
Everton will surely strengthen their forward ranks during the summer transfer window, and with more competition for playing time expected next term, Niasse has a lot of work on his hands.