United are guaranteed a spot in next season's Europa League four days before they play Crystal Palace in the FA Cup final but Dutchman Van Gaal's future is still the subject of intense speculation after two years in charge at Old Trafford.
“The issue is the amount of injuries in November and December, particularly in the two full back positions,” Van Gaal told reporters.
“We need creative, fast attackers and we have to take care of that. When everybody was fit we were first in the league. That is the facts.”
There were a number of empty seats at Old Trafford for the last home game of the season and a few banners suggesting the club's supporters would be happy to see Van Gaal leave.
“The expectation is very high. Too high. We are a team in transition,” Van Gaal said. “I have tried to explain that.
“We didn't reach our aim. We have to qualify for the Champions League. We have still the FA Cup final to go. Everyone has to make up his mind at how we have done this season at that time.”
Van Gaal was at least happy with his team's performance against Bournemouth.
“It was a very good victory, we have created many, many chances in the second half and we played very well,” he said.
“We scored brilliant goals,” he added, referring to a well-worked effort by Wayne Rooney and another sparkling finish by 18-year-old striker Marcus Rashford.
United, however, scored only 49 league goals all season, their lowest return since 1989-90.
After winning 13 league titles under manager Alex Ferguson with attack-minded teams who scored goals for fun, that simple statistic alone should make Van Gaal worry for his future at the Theatre of Dreams.
Original source: Van Gaal defiant as United seal fifth place