#5 Alexis Sánchez (from Arsenal)
The potential switch for Sánchez from Arsenal to Manchester City was definitely one of the most popular open-secrets in recent English football history. Alexis looked certain to join Pep Guardiola's brigade, having played under the charismatic Spaniard at Barcelona too.
When City failed to wrap up the deal to bring Sanchez to the Etihad in the summer of 2017, it was termed merely as "delaying the inevitable." City were expected to comfortably bag the Chilean in the following winter transfer window. They were so close to signing him, that Kevin de Bruyne pretty much gave it away in an interview.
It turned out to be far from inevitable, as interest from fierce neighbours Manchester United eventually forced Sanchez to reconsider. The wages being offered by the Red Devils was extraordinary, and well over twice of what City were offering. In the end, Sanchez decided to head to Old Trafford instead, a move which made him the highest earner in the history of the Premier League.
With Pep and co. having cruised to the title anyway, and Alexis struggling to replicate his Arsenal performances, the Cityzens might feel like they dodged an expensive bullet. Either way, Sanchez was a tremendous talent to miss out on at the time.