The Brackley-based outfit had a torrid time in Sao Paulo, with strategy errors dropping Russell out of contention for the race victory, while Hamilton could only finish down in 10th after a poor qualifying.
Hamilton also only finished down in 11th in the sprint race, with Russell at least in the points up in sixth.
While Russell did manage a fourth-placed grand prix finish behind the two Alpine cars, the Brit was leading the race when Mercedes decided to pit him during a virtual safety car period, before an unfortunately-timed red flag strongly benefitted Max Verstappen, Esteban Ocon and Pierre Gasly, who all gained a free pit stop.
The incident happened during an aborted start to the main race, following Lance Stroll's unfortunate spin, which pushed the starting procedure back to 10 minutes before the race start.
Now, Mercedes trackside engineering director Andrew Shovlin has revealed how this start line confusion led to the team being given the fine, and how the penalty could have been even bigger for the team and their drivers.
"The issue was when we got the message for the restart, that was straight into 10 minutes to go," Shovlin explained on Mercedes' YouTube channel.
"Now, the tyres must be fitted to the car at five minutes to go, and that meant we only had a few minutes to get the tyres down to the car, get them onto the car, and get them checked by the FIA.
"The added complication was that the set that we had called for, which was not the set on the racks but a set on wheelie boards so we could move them, hadn't been bled down to race pressures at that point.
"So the engineers will be calling for different tyre pressures, the tyre technicians are then running around trying to make sure all the sets are done and these sets weren't done, so once we got them down to the car we were up against that five minute limit which is a serious penalty if you don't make that.
"The penalty we got was actually because we didn't have time for the FIA checks to be done," Shovlin revealed.