Everton came into this afternoon's match in the relegation zone after three successive Premier League defeats and were heading for another damaging loss when they fell behind to the Cherries early in the second half of this afternoon's game at Goodison Park.
A double substitution that saw two of the key performers from Wednesday's cup win over Sunderland enter the fray helped turn the match in Everton's favour as Tom Davies provided two chances for Niasse from which the striker scored.
It was the latest chapter in what is becoming a remarkable turnaround in the Senegalese player's personal fortunes — he scored his first Everton goal against the Black Cats three days ago and rescued his team today with two goals in five minutes.
“He's bringing more aggression," Koeman said after the 2-1 victory. "I think we needed, in the second half at 1-0 down, to have another striker close to Dominic [Calvert-Lewin] to press a little better than we did before.
“And you know he's really a direct striker, he's in the box, he's fast and he scored a great first goal. He won the ball first in the midfield and he played the one-two and he scored a fantastic goal.
“And all the credit is to Oumar because that's life — when you get your chance you have to take it. He did last Wednesday and he did again today.
“When [a player] is being productive like Niasse you would be very stupid not to count [him in] for the future,” the Dutchman concluded, indicating that the 27-year-old will very much be involved in the first team going forward.
'A big win'
Koeman acknowledged how difficult a contest it had been for his team prior to the personnel changes that helped swing the game.
Davies was introduced at the expense of Davy Klassen and Niasse replaced Wayne Rooney, who had had to be patched up in the first half after sustaining a gash to his eye, while Kenny came on later for Cuco Martina.
“It was a difficult game,” the manager reflected. “I think we played well in the first half but we didn;'t create many chances.
“We took the right decision [at] 1-0 down to play in a different system with two strikers and to play a little more direct and that was important to change the game, to have more domination and more aggression. And finally we won the game.
“Sometimes substitutes can bring a lot and [they did] today but I think it's more credit to Niasse, Davies and Kenny because they did a good job after a difficult time in the second half.
“1-0 down, under pressure, I think the boys showed great character and the spirit we showed in a different way than the way we usually play. Okay, we changed and turned it into a win it was really important.
“It's always a different world after a win. You always have key moments in the season and today really was a big win that will give everybody a boost.”