Since he earned 10th place at the Russian GP, Russell has finished the last five races in 15th, 14th, 16th, 13th and 17th positions.
He’s also struggled of late to match his early season pace in qualifying, having previously been guaranteed to at least make Q2.
Despite failing to score in recent races Williams still looks set to beat Alfa Romeo to eighth in the World Championship, as it holds a 12-point advantage.
“I think everybody within the team is a little bit frustrated at the moment,” he said when asked by Motorsport.com. “I think we need to go away and understand what's changed.
“I think we've got a few indications. We normally had difficult Sundays but we had really great Saturdays to sort of compensate, and it's easier to hang onto a position than attack for a position given our car pace.
“But for whatever reason, the pace hasn't been there on a Saturday either, so we need to make the most of it in these last two and make sure we seal that P8, because that's the main thing for us at the moment."
Russell’s Qatar GP was compromised by a front left tyre failure that led to a slow lap back to the pits and an extra pit stop. However prior to that he had been able to run as fast as he could.
“At this track it was incredibly impressive how hard you could push,” he said. “It was relatively smooth, which allowed the drivers to really really push flat out.
“Probably from my whole F1 experience, this was the race where it was the highest tempo, if that makes sense, in terms of how hard you could push. That was really enjoyable, but obviously it didn't work out for us today.
“It's quite surprising. The rears you could probably have driven back to the UK on. Wear, it was pretty much just the front left.”
After qualifying Russell had made it clear that the team was struggling to get the tyres to work in Qatar.
“The limitation we’ve had was switching the tyres on,” he said. “If you look throughout all of practice every single lap we were improving. Even FP3, in the middle of the day, the sun was shining, and we improved on our third time lap, which is unheard of especially in the Middle Eastern races.
“Q1 we did the fast slow fast sequence and I improved both times on the second lap. Q2 we sort of put it all on the table for that one timed lap and just couldn’t get the tyres working for the first two corners and that sort of sets you up for the rest of the lap.
“So we need to understand why that is, because usually we excel in these conditions.”