Manchester United manager Louis van Gaal said referees needed to understand the character of players after midfielder Juan Mata was sent off for the first time in his career in the 1-0 defeat at West Bromwich Albion.
Van Gaal, who called his side's loss "a big blow," saw Mata dismissed for two bookings by referee Mike Dean and claimed "an experienced referee is better" in such circumstances.
Mata, sent off after 27 minutes, was booked for encroaching at a free kick taken by former United midfielder Darren Fletcher and then given his second yellow card for a foul on the Scot moments later.
Dean appeared to have no choice but to book him on both occasions, but Van Gaal told Sky Sports: "The first yellow card was a stupid yellow card because you know in advance that it is a yellow card.
"The second, you know you have already one yellow so you have to take that into account. You damage your team.
"But a referee has to also know the person who makes the tackle. Juan Mata never hurts an opponent. I asked him how many red cards had he had. He said: 'None, that is the first.' I assumed that already.
"You have to know the character of the players. That is why an experienced referee is better. He knows the players better, knows the game better.
"Is a foul always a yellow card? You saw the first three tackles by West Bromwich Albion on our players. There were no yellow cards. The decision was the turning point in the match."
Van Gaal said the loss at The Hawthorns was a big setback and added: "These kinds of matches you have to win."
Salomon Rondon scored in the 67th minute, ending United's run of four wins in a row in all competitions.
Defeat left Van Gaal's side sixth in the table, three points behind Manchester City, who have a game in hand. They had only one shot on target, which came in the third minute.
The manager said: "We have played 60 minutes with 10 men against 11 men. This is our fifth match in 14 days, I believe. It's very difficult for them to play against 11 players.
"That's the reason we lost, because we didn't give many chances away in the first half or in the second half. The only chance, more or less, was the goal.
"What can I say? It is a great pity we had to play with 10 men against 11 men."
Fletcher appealed to the referee after both incidents involving Mata, but stressed: "It was not looking to get him sent off. It's just a reaction.
"I hope they [United] pick themselves up from this and go on to finish in the top four."
United midfielder Michael Carrick said: "We wanted to carry on our form and results of late, so to lose is very disappointing.
"It's a tough game here anyway, and losing a man like we did makes it even more difficult. It changed the game."