Although the Finn had qualified a strong third, a slow getaway off the line meant he was sixth after the opening laps. Bottas still managed to remain in podium contention until his first stop saw mechanics fit three softs and a medium compound tyre on his FW37.
The mistake did not prove too costly in terms of lap times but the 25-year-old still had to serve a drive-through penalty, which dropped him down to ninth by the chequered flag.
“I am clearly disappointed with what has happened to Valtteri,” said Smedley. “As a team we have made a mistake, and on behalf of the team I am very sorry that we cost him what could have been a podium position.
“There will be an investigation into the processes in place to understand what happened fully, and to put in place a procedure to stop this happening again.”
While Williams’ error certainly hurt its chances of a good result at Spa, Smedley admits that a poor start to the grand prix and greater competition also made life harder for the British squad in the Ardennes.
“The rest of our race was dictated by the lack of pace in the first stint and from then on we had to fight our way back. The big difference at this race was that there were five teams all with very similar race pace.
“Unfortunately though, because so many cars were close in performance, the result was dictated primarily by what happened in the first stint when we were struggling.”
Click here for Sunday's gallery of the Belgian Grand Prix at Spa-Francorchamps.