For the most part this season, it's been the Dragons forcing teams to make errors but on Sunday at ANZ Stadium, the Rabbitohs gave them a taste of their own medicine.
The first-placed Dragons, who had an 8-1 record leading into the game, have had a charmed run with injuries, only using 21 players all season.
But that took a turn for the worse in the lead-up to their ANZ Stadium clash - St George Illawarra had a disrupted preparation as several players were hampered at training throughout the week and put in their worst performance of the year to lose 24-10.
McGregor was not using their unsettled week as an excuse and was adamant the Rabbitohs beat them fair and square at their own game.
"We've been winning games through forcing errors on the opposition and they turned that around today and done a little bit of that on us so full credit to them," he said.
"We had a few blokes that didn't train through the week and that's the first time that's happened but that's not an excuse.
"They're a good side. We knew before the game that we were playing some quality opposition.
"They've got some big powerful forwards and some speed out wide and good experience through their whole side."
Halfback Ben Hunt was troubled by a corked leg in the second half but manager to finish the game but Jack De Belin left the field in the 54th minute after aggravating a hip pointer injury.
McGregor said the Dragons learnt a lesson about the importance of preparation for blockbuster matches.
"He (Hunt) got a cork to his leg so he limped through the back end of the game but he'll be right," he said.
"Jack was one of the guys that didn't train all week ... we used two interchanges on it so there was a bit of a lesson there.
"I'll definitely have a really good look at it there's no doubt in that. You certainly need to learn from losing and winning."