The Red Devils suffered shock defeats to the likes of Swansea, Leicester and West Brom this term, but lost just twice to Chelsea, Manchester City, Arsenal, Liverpool and Tottenham.
And Van Gaal believes his side must become more consistent next campaign if they have any chance of competing for the title.
"When you see the results we've had against the other top-six sides, they are not so bad," the United boss said,
"It's against the little clubs, who fight, defend and park the bus, that we have to be cleverer. That is what has made the difference for Chelsea this season."