I don't know why folk feel Moyes doesn't have a winning mentality.
The times in question have generally been against far superior competition, such as the FA cup final etc, but how many times now have our 'budget squad' beaten the top sides? How many times have we turned City over? If Moyes managed United, I'm fairly sure United would be in good hands.
Moyes took a taxi into a Formula 1 race and over time has replaced every part of that taxi into a finely tuned racing car. He might be a few horsepower short of the top sides, but those top sides see him in their wing mirrors for sure, and every year they know if he had more funding, they'd see his proverbial indicator flash and pass them on the outside.
It's great saying those already with the fastest cars have a winning mentality, but put Ferguson, Mourinho etc in that taxi, and see if they would have gotten over the finish line, nevermind win the race.