I know they beat Arsenal but I reckon Arsenal have still picked up more points in the last 5-6 games. Could be wrong.
red Mancs - 4 wins 2 draws
Arse, Chelsea, Newcastle - 4 wins, 1 draw, 1 loss
Blue Mancs - 4 wins, 2 losses
Southampton, Liverpool - 3 wins, 2 draws, 1 loss
Extend that to 8 games, and you have 2 losses for Utd to throw in, while Arse have an extra 2 wins