Manchester United won again on Sunday. It was the club’s sixth consecutive victory, carrying the Red Devils solidly into third place in the English Premier League. After the match, Manager Louis van Gaal sounded less than pleased. It was a 3-0 victory over old rivals Liverpool, but he accentuated the negative.

“In spite of the goals, we gave away a lot of chances and that was every time when we gave unnecessary balls away. That’s what we’ve got to improve.”

Van Gaal was describing the most notable aspect of Manchester United’s win streak. The club is winning matches without putting forward particularly convincing performances. United controlled the run of play against Hull City for 90 minutes and kept Crystal Palace in check without too much difficulty. But in the other four matches, against Arsenal, Stoke, Southampton and Liverpool, the result could easily have gone the other way.

In fact, over these six matches, Manchester United has conceded overall better quality chances than it has created. There was a run of time between the Southampton and Liverpool matches when United had scored four of its last five shot on target. The following graphic shows the chances created and conceded by United. Black boxes mark goals. The array of quality chances (six from inside the six-yard box) which United’s opponents have failed to put away is spectacular.

Certainly, keeper David De Gea deserve his share of the credit. Big saves against Southampton’s Graziano Pellè and Liverpool’s Mario Balotelli helped preserve points in both matches. But at the same time, United has benefitted from Jack Wilshere scuffing a big chance and Mame Biram Diouf knocking a rebound right into defender Ashley Young when De Gea was out of position.

Research by Colin Trainor has shown that very few keepers can maintain a save rate more than 25 percent above average. De Gea’s shot-stopping has been tremendous, but some regression is likely both as his hot streak cools off and as opponents start putting better shots on his net.

But how much is United likely to drop off? To create a set of comparisons, I took a look at other teams which massively overplayed their expected goals over a six-match streak. Did these clubs maintain their performances during the streak? For the most part, they did not.

Manchester United has a plus-ten goal difference over its last six matches but a minus-one expected goals difference. In the English Premier League since the 2009-2010 season, there have been 18 streaks of six matches in which a club had a GD more than eight goals better than its xGD. These clubs averaged a plus-two xGD and a plus-eleven xGD during the streak. In the next six matches, the clubs on average managed just a plus-two goal difference. It was expected goals, not real goals, that best predicted future performance.

So, again, it seems unlikely that United can keep up this pace. Van Gaal’s side has been winning through a combination of hot finishing, excellent goal-keeping and poor opposition shooting. If United cannot tighten up the defense in particular, the next couple of months may be tough.

But to finish on a more positive note for United, regression to the mean can be a complex subject. To what mean, precisely, should United regress? The Manchester side has one of, if not the largest wage bill in England. The talent on the club may be somewhat overpaid, but it is undeniable. Perhaps the mean to which United will regress is not the club’s roughly 0.500 expected goals ratio but the 70-plus point side that United’s huge payroll should correspond to.  This hot streak has given Van Gaal a nice cushion, and he has time to figure out tactics and team selection which produce better underlying performances. If he does not get it right, however, United is likely to fall.