The summer transfer window is about to open, so let's look at the 10 most expensive transfers by position -- goalkeepers, defenders, midfielders and forwards -- through 2021. I awarded a (highly subjective) grade out of five based on what we know now. In other words, with the benefit of hindsight and knowing what happened next, would the club make the same decision to sign a player again?
I took into account not just individual performance, but also age at the time, transfer fee, longevity (money recouped if the player was moved on) and injuries (sometimes it's nobody's fault).