Honestlynwatching them I wouldn't have thought that was the case as both he and Valencia looked like they were playing with a rubber band attached to them that only allowed them to go so far. Then him telling Mitchell off for going too far forward would indicate that wasn't really the case but if Shaw is saying that then it must be true. Where did you get that from? I'd love to read it as the fullbacks have been a spot of contention for me all year.
Here is the article
http://www.manchestereveningnews.co...l-news/man-utd-news-shaw-southampton-11766784
When you have a full back or even a CB surge forward, you need to have enough cover behind him so as not to be overly exposed on the counter. Mourinho, as far as I can tell, wants at least 3 players to maintain the defensive line, usually a combination of CB, DM and/or LB/RB. The details would likely depend on the scenario and quality of players e.g. you could have the 2 CBs + the opposite fullback, or you can push CBs wide and the DM drop into the middle or to a side.
The other and more important criteria is that the attacking full back should have the pace, discipline and positional sense to help the defense recover its shape as quickly as possible (which is not necessarily same as him going back to his normal position). Unfortunately, such quality of full backs are in short supply (with Lahm being one of the best in recent time). At Madrid, Mourinho had to make do with Arbeloa who was too slow and Marcelo who couldnt defend his own life. At Chelsea, he didnt have any solid option at LB and had to move Azi over, keeping in mind there was an aging terry in the middle.
What you often see are full backs that push forward with abandon like wingers, leaving the rest of their team mates to try and clean up after them. For example, Juve's first goal can all be traced to Sidibe being caught upfield and not helping his defence to recover, which started a chain reaction that moved other players out of position and led to Juve scoring. For Mourinho, conceding such a goal is not permitted
Last season, Mourinho did not have a DM with the full toolset to cover side to side, which would have allowed the two full backs to push forward more. Worse still is that, of the various options at full back, only Valencia has the pace, engine and discipline to overlap without overly exposing the defense. Shaw has the pace to recover but his positioning and awareness leaves much to be desired. This should improve with more game time and experience. Darmian, Rojo and Blind simply lack the pace to recover in time, and both Darmian and Rojo are so clueless upfront that there is really no point in them going forward.
I think with a quality DM, and Shaw staying healthy (or new LB), I expect us to see more attacking forays from both fullbacks