The Dane was heard to query a decision to pull out of a lap during Q2, in which he was slightly up on his delta from his opening outing of the session on the run up to Massenet. He was given the command to back out as early as Beau Rivage, and instead prepare for another attempt next time out.
But this lap fell shy of his initial marker, a 1m11.725s, which consigned Magnussen to an exit from the second part of qualifying, in which he could only qualify 15th - three positions behind team-mate Nico Hulkenberg, whom he had outpaced in Q1.
Magnussen was furious with the decision, one that he reckoned was for "no reason", after coming a cropper amid traffic at the end of the session.
"We carried an extra lap of fuel in case the first push would have got traffic. We could abort and go again," Magnussen explained.
"We left the pits with time to do that. And I started the lap in the window, I gained more than one tenth in turn one. So looking really good and we aborted the lap for no reason and then started the next one. I had traffic the whole lap."
"For some reason we aborted that lap, even though we were up on lap time."
Explaining where he thought the lap might have shaken out, Magnussen noted that the Haas had the pace to contend for a Q3 berth - and thus reckoned that the team had missed a "pretty big" chance to stack the odds in its favour for Sunday's race.
He hinted that this was a long-held frustration with the decision-making on the Haas pitwall, stating that it was "the same every day and weekend".
"In Turn 1 I gained more than one tenth, so I don't know," he reflected. "I think we were up for Q3 today. It looked like we had the pace. Q1 looked like we could do that, so I feel like a pretty big opportunity missed today.
"It seems to just be the same every day and weekend. So we've got to manage it. We have to look into what we can do better, because we can't keep doing this."