Manchester City's last three signings have averaged a spend of £60m, yet each of them have something negative in common.
Riyad Mahrez in 2018/19, and then Rodri and Joao Cancelo last season are three of City's most-expensive signings of all time - but they all failed to hit the ground running.
Mahrez needed a season to adapt to the step up from Leicester, despite arriving as a player who had already won the Premier League and had Champions League experience. Cancelo only showed his best form in the final games of the season, while Rodri performed slightly better, but there is definitely more to come from the record signing.
So if City are to spend another potentially club-record fee on a new defender this summer, they can't afford for a season of adaptation. They need him to make an impact immediately.
Look at Liverpool, whose signing of Virgil van Dijk has been analysed over and over again, but there's no doubt he was the missing piece in their problematic defence and has been a crucial factor in their recent success.
And over at Manchester United, Ole Gunnar Solskjaer's side looked destined for another underwhelming season finishing outside the top four until Bruno Fernandes arrived.
The Portuguese playmaker, like Van Dijk for Liverpool, was the missing link for United, bringing out the best in other players as well as producing a number of influential performances to help Solskjaer's men reach the top four and three semi-finals.
So if City are to spend big money on a new centre-back - potentially Kalidou Koulibaly - they need an instant impact themselves.
With Koulibaly especially, the 29-year-old should be at the peak of his career, and is at an age where he and City just couldn't afford a season to get up to speed.
If the new man can immediately step in to Guardiola's defence, improve the communication and provide the leadership which was lacking last season, then City will know whatever money they spent was worth it.
And like Van Dijk and Fernandes, they will hope the confidence will flow through the team and the problems of last season can be solved with one addition.
