I mean no, you can’t.
We literally did the correct thing signing Branthwaite from Carlisle didn’t we. Or Dom from Sheff Utd.
Long term ofc we did, but neither of them walked into the team, Jarrod and DCL both took a few years to start to feature.
But unless you wanna turn into Zatara mate with a squad of prepubescents then you can't always sign the player 'before' they've actually shown they can handle that step up.
Take our business this season - Tim could very well turn into one of those players, but premier to premier there's a huge premium, if you think palace would sell him to us for 1m you're living in cuckoo land, they gave a massive fid punt and btw have a big sell on fee because they are in essence a sister club almost.