A 3-5-2 would certainly be unorthodox in the EPL, but Manchester City does have the squad for it.
The key here is Pablo Zabaleta and Aleksandar Kolarov. Having players on the wings who can be trusted to put in a proper defensive shift is essential, and they are two such players.
David Silva is City's best central midfield distributor, but also still has the ability to play a more attacking role. This formation, with two true box-to-box midfielders at his side, allows him to position himself wherever he'd like.
Stevan Jovetic also really allows this formation to work, as he is one of the few forwards who can shine with a partner. His positioning and eye for the pass can be put to great use here.