Weird formation: how to make it work?

[goalash]

So, I was struggling to find a working setup for my South Korean, highly technical club team and suddenly, in like 8th friendly game, wonders happened.

I was trying to utilize a very good trequarqista on the STC position, bit nothing seemed to work. And, as it stunned me, this worked almost perfectly (sorry for no prtscr):

 

                           T (A) PF (S)

                              SS (A)       W (S)

 

    WB (S/D) DM (D) DM (S)

                    BPD (C) CB (D) IWB (D)

                             SK (D)

 

PI: DM(S) - get further forward, Ti: whipped crosses, lower line of engagement

I’m still unsure about the roles for STCR and AMC (logic tells me he should be an AM(S), but I need regular runs into the box here). What do you make of it?