Simeone won the league and made the final of UCL twice before he spent big, and he only did so to replace players they sold big as well. Klopp's Dortmund is a good example, or Otto's Greece/Kaiserlsuatern etc. There are many examples of managers performing way above what their squad is capable of without winning things too. Potter's Ostersunds, Mourinho's Porto (the Uefa Cup one) and even Wenger's first season. He was absolutely influential and transformed the squad. Even Ranieri manage to play to Leicester's strength and got the best out of very limited players. I am sure Jones can name even more examples than this.
The common similarity between these great managers is that the players looked great under them, then when they left or the players left the club they looked crap again.
There's always a thinking that a manager need 2-3 seasons to transform the squad and get the players he want to play his type of football here. Otherwise we can't blame him for playing shit football and defensive lineups. Those myths are rubbish IMO. Most managers don't need much time to impose their style onto the team once they take over. Look at how Potter transform Brighton's playing style which is completely opposite under Hughton within a few games. Bielsa at Leeds, Rose at Gladbach, Gasperini at Atlanta in recent examples to name a few, all of them don't need an entire new squad to play attacking football. Their style were evident within a few games.
