Of course Marotta has his share of fault for not bringing a top CF. But look, it was pretty difficult.
Suarez - main player in Liverpool, would have to change to an inferior league, they wouldn't let him go for nothing. Pretty difficult, not Marotta's fault.
Higuain, the same.
Van Persie - huge wages, stronger league, 29 yrs, injury prone, United payed like 30M for him. Not easy and I don't really know if it would be worthy.
Cavani - impossible.
Llorente - very very hard - Athletic is tough, they are selling Martinez... Llorente is not worthy 36M in his last year of contract at all.
Jovetic - the most doable one - even though very difficult. Here I think Marotta made a mistake, he should've been more aggressive. Anyway it was pretty difficult.
Dzeko - City didn't sign anyone so far, would've been a realistic option but without a substitute he's not in the market.
So it was a tough job. In January, Dzeko/Suarez/Jovetic can be fed up with their situations and the signing will be more realistic. I think it didn't happen so far not because of lack of money, but because Marotta didn't want to overpay. These great players have to push for transfers nowadays, that's our chance of landing them. So january is still an option, if any of them is unsatisfied