I know someone who played under Moyes and he always says that this was his great skill as a manager. According to him, the players didn't love him, but they respected him and loved playing for him, because he was straight with you and expected exactly the same things from all his players. He didn't care if you were a 19 year old making your debut, a journeyman pro, or the star of the team, he expected you to put a shift in and follow instructions. If you did, he was happy, if you didn't you heard about it.
*edit* My personal opinion is this is why he failed at United, because their players didn't buy into that mentality and some players thought they were above others. He didn't know how to deal with that and so the whole thing fell apart for him.
My Manc supporting brother - in - law always said his biggest mistake was getting rid of certain backroom staff who he shouldn't have, and trying to change behind the scenes in one swoop.