This does apply to the whole ticketing ploy principle, HCT in particular, because in this case IST is a fortress hub for TK and so ending (or staying, then returning from) there would fetch a higher fare; using it as the cxn would lower it.

If OP can do a o.w. on TK for 1/2 that $1,200...then find a good deal o.w. back to ORD on another carrier, then he can do it HCT. And that's a big IF...