Do we or do we not bring in a better player than Garnacho at his position? If the answer is yes, and here is his name (fill in the name here), and it only requires that we spend let's say 20m of the 40m we hauled in when we sold, Garnacho, we're in the black 20m on the deal.
Unless we have a youth player, the next Garnacho, ready to step up to the first team and perform at Garnacho's level, are you telling me that selling Garnacho and netting 20m on the two transactions -- the sell and the buy to replace him -- really makes the difference between competing and not competing for major trophies?