Russell insists that the team's data suggests that, on paper, the FW43B is only faster than the Haas – except when it comes to qualifying, when the Englishman regularly makes Q3.
Russell enjoyed his most impressive qualifying session to date at Silverstone, earning eighth place on the grid for Saturday's sprint. He finished the event in ninth place, but a three-place grid penalty saw him start the Grand Prix from 12th, and he finished in the same position.
Russell suggested that his struggle to stay ahead of faster cars was further proof that it's hard to repeat his one-lap form over longer stints.
"Ultimately, I don't think we really deserved to be any higher than where we finished. I don't know how we keep managing to qualify so high," he said. "You know, we still on paper have the ninth quickest car in every single session except qualifying. FP1, FP2, FP3 and the race, we're the ninth quickest.
"And then somehow come qualifying we manage to put it inside the top 10 or top 12. So come Sunday, when you have eight faster cars, or whatever it is, starting behind you, it's so difficult to keep them there.
"I think the cars behind were three, four or five tenths quicker than us. And when you've got that sort of pace advantage it's easy.
"And they seem to be better on the tyres than us as well. So it was always going to be a race of looking in the mirrors and trying to keep these cars at bay."
Russell admits that he should be pleased with his recent results: "It's a little bit disappointing, always after the races. But I guess we've got to think, top 12 in all of the last four races except the one we retired, fighting for points in three out of four of those races, I guess we would have definitely taken that before this group of four.
"I think that [P12] is a fair result. And we probably didn't really deserve to be any higher than that is. It always seems to be the case, we're going backwards on a Sunday.
"And I don't think it's because we've done a bad job on a Sunday. It's just because we're somehow doing an excellent job in qualifying. So that's a little bit tricky."
Russell denied that his team is putting extra effort into qualifying at the expense of long run form, and suggested his one-lap performances are down to getting everything right and making few mistakes.
"We're not focussing on qualifying, we're focussing everything onto the race. So I don't know if we improve or the others make mistakes. When it's one single lap and the pressure's on, a one tenth or two tenths mistake makes the difference.
"Whereas in a race, you get into the groove, you get into the rhythm, and you find the limit over the course of a few laps, and then you can make hay at that.
"We just need to do a really good job with the procedures, getting everything right, the tyres in the window, right place on the track. And I feel confident in the car in that situation. And I think just between us all we do probably a better job than most, clearly."