Everton are renowned for their transfer disasters with Farhad Moshiri spending over £500m on signings since taking over at the club in 2016, but it's not only the players brought in that will make the Toffees owner regretful amidst the club's struggles.

The Merseysiders have also missed out on a number of opportunities to sign rising stars who have gone on to become serial winners playing for some of the biggest clubs in the world after failing to complete moves to Everton.

One player who was close to making a move to the club back in 2016 was Kalidou Koulibaly, who most recently joined Chelsea in a deal worth £33m to replace Antonio Rudiger, after having an outstanding career following his failure to join Everton six years ago.

According to Liverpool Echo, the 31-year-old was first linked to the club when John Stones was sold, however, Napoli constantly rebuffed any attempts made to sign the Senegalese defender, leaving Everton to look elsewhere to bolster their back-line.

Since then, Koulibaly has gone from strength to strength whilst the Toffees have struggled in the Premier League leading to a disappointing relegation battle last season which was largely blamed for the poor defensive performances displayed over the entire campaign with Jamie Carragher blasting their "Championship back four".

The former Napoli colossus has won the Italian Cup and Africa Cup of Nations, and has also been named as Senegal's Player of the Year twice since Everton set their sights on the centre-half, becoming one of the sought-after players in Europe, with ex-Chelsea boss Thomas Tuchel hailing the player "very rare" upon his arrival at Chelsea.

"Kali combines a level of quality, talent, level of personality, strength in set pieces – offensively and defensively, heading and the physicality which is very rare to find," he said.

In 2017, Michael Keane joined the squad at Goodison Park a year after Everton failed to secure a deal for the now Chelsea star, and it is fair to say that Koulibaly would have been a much better signing.

When you compare the two players over last season alone, the talented defender outperformed Keane in many attributes including pass completion (87.4% v 77.6%), won more tackles (43 v 35), a better dribble success rate (86.4% v 71.6%) and pressure success rate (41.8% v 40.8%).

With that being said, the powers at Goodison Park will surely be regretful they couldn't secure the signature of Koulibaly as his quality and powerful influence in the back four could've saved Everton a lot of worry over the last few seasons.