The Blues have been disappointing in recent weeks, with the defence coming in for criticism.
The Blues have been highly impressive going forward, with striker Romelu Lukaku currently top goalscorer in the Premier League alongside Jamie Vardy.
Defensively though, things have been poor as they've conceded goals freely, with their last two home games having seen them concede seven alone to Stoke and Leicester City.
And Nicholas says that a lack of toughness is something that is seriously harming Roberto Martinez’s side.
“They’re not tough enough, and they need to sort that out,” he told Soccer Saturday.
“They’ve had issues with Tim Howard, who’s a fantastic goalkeeper but he’s not had a great season. He’s on the edge of losing his place there.”
“I’m not saying they are a soft touch, but they can’t close out a game, they’re not clinical enough.”
If Everton are to improve defensively in 2016, they will be hoping that John Stones doesn’t have many performances like he did in the loss to Stoke.
The defender is arguably one of the best young defenders in the division, with him often being lauded for his performances in recent seasons.
He was far from his best against the Potters though, with his passing in particular something that was off in the performance.
The Blues will be hoping that was a one off and he can get back to his best quickly as they aim to move up the table sooner rather than later.