He’s a deep laying playmaker, but he’s not a defensive midfielder. His job isn’t to protect the back and to sit. The role of the defensive midfielder has evolved over the years and the Spanish have always had deep laying central mid players that set up play. As for your Flamini example, his defensive attributes outweigh his attack. He contributes more defending then he does attacking. He’s short, but he has the engine to keep running and but tackles in.
You have very narrow mind when it comes to player positions and duties. You know the difference between a striker like Henry and Bergkamp right? Or a RVP and Hernandez or Berbatov? Same goes for centre back partnerships. The Merts and Kosienly combo works because they have different ways of defending and their styles complement each other. That’s how football works. It’s the same in the middle of the park. Cesc isn’t suited to playing in a 4-4-2 formation. Not with the combos we’ve seen.
Also, in a 4-3-3, with the players we had and how we started to struggle to move the ball around, it would have been better to play him further back with someone like Rosicky, Nasri or Wilshere ahead of him and Song holding behind him. Denilson was weak on offence and defence. You can have a CB that does his fair share of defensive work, but in this day and age, you need one player to focus fully on defending and not cross too far over the half way line when attacking. There is a balance. If we had someone to focus on defence and someone that was comfortable picking out passes and keeping the ball moving then I’d say it’s okay to move Cesc that forward. It’s what they’re doing at Barca because he has Xavi and Iniesta behind him and they can pick out his runs, while Busquets is behind all of them playing a more defensive role.
Besides the middle of the park, we had many things wrong with the squad. It lacked balance on the flanks as well. Check out what other teams are doing and you’ll see the bigger picture.