Daley Blind of Manchester United
After a strong showing in his first season as Everton manager, Koeman was backed heavily with transfer funds over the summer, as the Toffees brought in the likes of Jordan Pickford, Michael Keane, Davy Klaassen, Gylfi Sigurdsson, Sandro Ramirez.
However, Koeman made a dismal start to the season, losing five of his first nine games, losing his job in October having been sacked after a 5-2 home defeat to Arsenal.
It now seems that Koeman had another signing in mind over the summer, as Dutch newspaper De Telegraaf report that he wanted to sign Manchester United defender Daley Blind.
However, Everton focused on other players instead, and prioritised pursuing a striker over attempting to sign Blind – and they ended up with neither come the end of the transfer window.
Blind, 27, joined United from Ajax back in the summer of 2014, and has filled a number of roles, including centre back, left back and left wing back during his time with the Red Devils.
Whilst he started the season as a regular under Jose Mourinho, he has been phased out of the side in recent months, and finds himself down the pecking order at Old Trafford.
Given that Koeman wanted a left-sided defender who could play at left back or centre back, Blind could have been ideal for Everton, but many are now left wondering what might have been after Everton looked elsewhere.