Premier League referees' chief Mike Riley says there were four instances of the "worst possible outcome" of the video assistant referee system in two weeks before the international break.
Riley told a meeting of the 20 top-flight clubs that on those occasions VAR had overruled perfectly good decisions by the on-field officials.
"We are far from perfect and we have to improve the way we do things," he said.
Riley's assistant Neil Swarbrick gave the system a mark of seven out of 10.
Riley added: "Part of the balance of understanding 'clear and obvious' [the terminology used to determine when an on-field error should be overturned] is that there will be times when we don't intervene and everyone thinks we should.
"But that is a better place to be than intervening and everyone saying 'you shouldn't have done that'.
"There are significant things we can do to improve, including better consistency in decision-making as VARs and the timings so we get minimum interference."
The four incidents Riley was referring to are below. See if you agree that the VARs got them wrong:
26 October - Brighton 3-2 Everton
What happened? In the 77th minute, a penalty was given to the hosts by VAR for a 'foul' by visiting defender Michael Keane on home striker Aaron Connolly. Neal Maupay converted from the spot for 2-2.
What was the match outcome? Brighton scored again in the 94th minute through Lucas Digne's own goal to win 3-2.
What they said: "If VAR saw something in our box, why didn't it see 15 minutes earlier the penalty for Richarlison," said Toffees boss Marco Silva. "Because of that my players are in the dressing room and don't understand.
"If they see one for one side then they have to see for the other side too. It was a clear penalty [to us]. VAR has to be the same for both sides."
27 October - Norwich 1-3 Man Utd
What happened? United were awarded a first-half penalty by VAR after a collision between winger Daniel James and home defender Ben Godfrey. Marcus Rashford saw his penalty saved by Tim Krul.
What was the match outcome? Despite missing two penalties, goals from Scott McTominay, Rashford and Anthony Martial gave United a 3-1 victory.
What they said: "It's quite obvious it was a big mistake," said Canaries manager Daniel Farke. "The referee was right and it was Daniel James falling on the defender. I don't blame VAR for this defeat, we were not major enough in the first half."
27 October - Arsenal 2-2 Crystal Palace
What happened? Gunners defender Sokratis Papastathopoulos converted from close range and thought he had won the game for Arsenal late on, but the goal was ruled out by VAR for Calum Chambers' 'foul' on Luka Milivojevic in the box.
What was the match outcome? Arsenal surrendered a two-goal lead as Palace hit back to draw 2-2.
What they said: "I didn't understand the referee and VAR reaction," said Arsenal manager Unai Emery. "For me there is no confusion - it is not a good decision.
"We deserved to win, we had a good reaction after they equalised, we scored but then they didn't count it."
2 November - Watford 1-2 Chelsea
What happened? A penalty was awarded to the Hornets by VAR after Gerard Deulofeu went down under a challenge from Jorginho with minimal contact. Deulofeu scored the spot-kick.
What was the match outcome? The Spaniard's 80th-minute goal proved only to be a consolation as Tammy Abraham and Christian Pulisic gave Chelsea a 2-1 victory.
What they said: "We're not in a great place with it," said Blues boss Frank Lampard. "Any [decision] that takes that long means they aren't sure, so why aren't we using screens on side of pitch?
"But if we are saying they are grey areas and we are overturning decisions because one referee somewhere else thinks it was more of a penalty than the referee on the pitch, then I think we are in a really dangerous place."