Mata - class, but still to be proven as suiting the system at United. Shaw - very young and last season was his 'break-out' season, like our Manquillo and especially Moreno, still to show he can cut it at a top club and continue his improvement, signs are good though. Herrera - looked good in pre-season, but then he had a lot more time on the ball as he received in Spain, not a good sign he was subbed off in his first PL match (unless he was injured ? I didn't hear anything). Rojo - not a top class player but something you needed, a good utility player (CB, LB, WB).
Definitely agree on you needing a high quality CB and CM. I don't think it's going to be Vidal (despite your very low offer) and Strootman in January (at best and returning from a major injury) could be too late to save your season.