If we're looking into American players still since Tessman failed i really rate Tyler Adams as a good backup for holding mid given the Asllani experiment has appeared to have failed. He can play elsewhere in midfield and Im pretty sure he could function as a LCB or RCB given he can be deployed at LB/RB. Pretty sure he's captain of the USMNT too. transfer markt says 15 mil so hes likely out of our price range for a rotation player though.