The Red Devils twice came from behind to force a 2-2 draw with the Baggies at The Hawthorns but van Gaal opined his side were much better than the scoreline suggests.
"I'm very disappointed because we played our best match of the season and the result is not good enough," he told Sky Sports.
"I think we could have won but that doesn't count in our world so that's why I'm disappointed, but I also have to be happy because we created a lot of chances and only two shots from West Bromwich Albion turned into goals.
"We gave it away because of our individual errors and that's a pity...
"I've seen on the training ground now that we are better, the players understand the formation more and I've seen it today which is why it's such a pity we didn't get the result we deserved."
Saido Berahino then scored his sixth goal of the Premier League campaign in the 66th minute before Daley Blind netted his first goal for the Red Devils with a cool side-footed finish from outside the area in the 87th.
For breaking stories and all the great banter like us on Facebook: facebook.com/tribalfootball