Russell was second-fastest aboard the Mercedes W15 during FP2 at the Jeddah street circuit before qualifying in seventh place, but he would only go on to gain one position during the 50-lap race.
That place came courtesy of one-time leader Lando Norris dropping to eighth after running out of sync, the McLaren driver having stayed out for a longer first stint while others capitalised by pitting during an early safety car that was required after Aston Martin racer Lance Stroll clouted the barriers and retired.
Russell likened the race weekend to the Bahrain season opener. There, team-mate Lewis Hamilton led a 1-2 in FP2, Russell then qualified third and finished the GP in fifth.
But rather than this dropping back being owed to other teams improving as the round wears on, Russell has attributed it to Mercedes “getting slower” across the sessions.
“We're still really trying to understand this car because we have shown true performance at points over the last two weekends,” said Russell.
“FP1, straight out of the box, we were top of the timesheets and always in the top three. FP2, P2. Then, both weekends, the pace just falling away from us. That hasn't been our competitors getting faster; that's been us getting slower.
“So, we need to understand why that is. But it's fine margins now.
“It’s so close with ourselves, McLaren, Aston. Charles [Leclerc, Ferrari] is just a smidge ahead.
“We just need to tap into it a bit more.”
Russell crossed the line in Saudi Arabia almost 40 seconds behind winner Max Verstappen, with Sergio Perez and Leclerc completing the podium.
He was also beaten by McLaren’s Oscar Piastri and Fernando Alonso in the sole surviving Aston Martin.
Russell and Hamilton had complained about their cars bouncing throughout the weekend, but the former reckoned the problems for the W15 were more widespread.
“I think there's more to it,” when asked by Autosport about the primary cause of the performance dropoff. “It's so complex these days. These cars are so complicated.
“When you couple that with the tyres, the tyres are very difficult as well. Right now, I don't have the answers.”
Russell did, however, maintain that the field remains “pretty tight” behind clear pacesetter Red Bull.
