Wayne Rooney
Wayne Rooney joined Everton on a two-year contract in July 2017Getty Images

Everton manager Sam Allardyce has warned Wayne Rooney to step up his game or risk being dropped from the team after the former Manchester United forward expressed unhappiness over being substituted during the Merseyside derby.

Rooney was visibly angry after being taken off in the 57th minute of Everton's goalless draw with Liverpool at Goodison Park on April 7, with television cameras capturing him mouthing off a stream of expletives on the Toffees bench.

It was the second successive time Rooney had been substituted before the hour-mark of a game after he was replaced in similar fashion during the 3-1 defeat against Manchester City.

Allardyce said he analyzes every Everton player's statistics and vowed to drop anyone who is not matching up to the standard he demands.

"It's simple for me," the Everton boss was quoted as saying by the Daily Telegraph. "There's my eye in the game and then there are the stats after the game. When those stats match what I've seen, for any player, it's where we make our decisions.

"We talk to the player about that situation, whoever it might be, and say levels have to be lifted. And when that continues to happen, no matter who it is, whether it's Wayne, Phil Jagielka, Tom Davies or whoever, you get left out of the team."

Allardyce added that he would continue to use Rooney in a midfield role given the poor form of Davy Klaassen, but admitted that the former United player can at times struggle to perform against high quality opposition.

"I can agree with you, to a certain degree, that Wayne struggles against the very best opposition," Allardyce said. "He didn't play very well in the first half against Manchester City but, before that, he had been outstanding and we had been a little bit short in ­midfield in recent weeks anyway."

After the Merseyside derby, Allardyce said he had taken off Rooney early in the second half as he needed "more legs" in midfield.

"As talented as Wayne is and as good as he is on the ball, we needed to get about the pitch a bit more, and he'd done his job," he was quoted as saying by Sky Sports.

"That's the way the game goes, nobody is too big to be brought off. It's because it's Everton v Liverpool isn't it? He's bound to be disappointed, there's no doubt."