“Especially in those circumstances. We’re all pushing so hard, we’re working so hard with this car and we’re just not getting the most out of it.”
Russell will start the race behind Alpine’s Pierre Gasly and Haas’ Kevin Magnussen, who will line up in the American team’s highest-ever starting position for a grand prix.
Mercedes team-mate Lewis Hamilton, meanwhile, will start from 13th place after being a surprise elimination from Q2.
Hamilton began reporting pace issues towards the end of Friday’s practice but Russell believes Mercedes’ troubles worsened during qualifying.
“Sometimes it’s fine, sometimes we’re really struggling with it and, yeah, fortunately, we’ll be starting P6 tomorrow, I’ll take it.
“You can say there is no luck in it because we got the time on the board. I don’t really know what to say to be honest, it’s a tricky one.”
The Mercedes duo were reporting issues with pace in the straights and vibrations through the steering rack during FP3 on Saturday.
“I know why [things have been difficult since Friday,] the car is not performing as it was and the feeling from it isn’t as good as it was in FP1.
“In FP1 it was smooth, it was pretty clean. Obviously, we were top of the time sheets but we ran right to the end of the session.
“But we thought we would be around three-tenths behind Red Bull and it’s seemingly just got a little bit worse as the weekend has progressed and it’s rare that happens with us because normally it’s the other way around.”
Mercedes have a troubling history with the Miami International Autodrome, having suffered the same loss of pace from Friday into Saturday during the event’s inaugural race.
Then, the return of porpoising stopped Russell from attacking the corners during qualifying. But this year, the team face fresh problems to solve.
“I don’t know, it’s a bit of an outlier at this track, this new tarmac is unlike any others. But need more, we’re working for more.
“We’re working so hard to achieve it and it’s not quite coming together at the moment.”