Had we selected Robertson instead of Hrustic that would have left us with one less RW and one extra CM. Yes Hrustic can play CM but his best posi is RW. And yes Robertson could theoretically play RW (not that ive ever seen or heard of him play there) but he is obstensibly a CM/DM.
And the 2 players behind the striker are not AMs they are narrow/inside wingers. Even if you want to argue they are AMs, Robertson has played majority of his games for Cardiff in the double pivot, not at AM. Checking on Tramsfermarkt he played a total of ONE match last season at AM and ZERO on either wing. He is a CM/DM mostly.