The Dutchman’s side are currently a point off the top four at sixth place in the Premier League and are a replay away from a Wembley FA Cup semi-final.
He believes the injuries have had a heavy impact on the team.
“It is dead easy to be critical,” he told Sky Sports.
“You have to be realistic about some things – the number of injuries he has had: Phil Jones has played only seven games this season, Ashley Young, (Antonio) Valencia, (Luke) Shaw, these are big losses.
“It doesn’t matter which team you are, if you have players missing of that caliber it has to have an impact on the team.
Luke Shaw‘s leg break in the Champions League group stage defeat at PSV Eindhoven earlier in the season has clearly effected the Dutchman’s side as he was such a crucial player but United have had to deal with injuries every season.
The reason it has affected us so much is because of the thin squad and that was van Gaal’s choice. It’s a hard thing to balance – having a squad strong enough to cope with injuries but small enough to give youngsters an opportunity, it’s an almost impossible balance to find.
United’s squad isn’t strong enough, every fan will be quick to admit that and as brilliant as it has been to see these youngsters coming through, there isn’t enough quality around them and we are relying on them too much.
Under Fergie, we had world class stars and youngsters dotted in between them. We need to find that balance again in order to be challenging for titles and that means we’ve got another busy summer ahead.