That's because last season out first team were very good, our issue last season was a lack of depth. When you lack depth then it makes sense to acquire back-ups.
1 Guus has said he wont stay many times
http://www.skysports.com/football/news/11668/10175788/guus-hiddink-having-a-ball-but-has-no-plans-to-remain-as-manager
2 Appointing a former player instead of an experienced manger, as our new manager is just plain dumb
Chelsea limped to the title last season, the difference in quality in England is nowhere near as bad as in Spain.
Jose didn't play kids because he is to scared to take risks. He has no tolerance for mistakes, kids make mistakes.
To be fair Simeone has to be pragmatic to keep up with Barca and Real, as he has nowhere near as much money, nor players like Messi or Ronaldo. I would be surprised if he was as pragmatic if he came here.
The biggest gripe I had with Jose was that he didn't even give players chances at Chelsea, Mata was our best player 2 seasons in a row and he only played 90 min twice under Jose. If Jose gave these players proper chances, then decided to get rid of them it would be more acceptable.
Formations are listed here
http://www.transfermarkt.com/atletico-madrid/spielplan/verein/13/saison_id/2015
an example
http://www.transfermarkt.com/spielbericht/index/spielbericht/2594483