They are thinking of trying to write a guide, but when you consider how much there is to cover, its no easy thing. You're basically looking for a short version of TT&F 10. No easy feat.
The game certainly needs more transparency, but also, people need to take a step back. Stop trying to beat the game, and aim to play the game. That is the single biggest difference between. FM12 and FM13.
I dont think you need to know the ins and outs, but without a guide, you definitely do need to understand footballing concepts.
The best 2 questions anyone can asks them themselves is Why? Why are you making that particular decision (Why are you playing an AML as an side forward? because i want him to score goals by cutting inside) and How? How will you achieve that (by creating space for him to attacking into by having a treq or a support forward, or by having a winger on the other flank and and having attacking enitre forward on roaming.
It's a game but its also edging closer to a sim, after all the ultimate aim is to fully replicate that. But it hasnt got the technical guide of a sim, and that for me is its biggest issue.