Williams failed to deliver "across a number of key elements" in 2016, according to deputy team principal Claire Williams.
Since the introduction of the new power unit regulations in 2014, Williams had been very competitive, initially beating Ferrari to third place in the constructors' championship before getting the better of Red Bull to retain that position a year later.
However, 2016 has seen Williams slip back in the pecking order, with Force India beating it to fifth place in the constructors'. Williams believes there were crucial areas where the team failed to perform which need addressing ahead of next season.
"I don’t think we’ve delivered where we needed to deliver this year, across a number of key elements," Williams said. "I’m not going to go into detail on the areas of weakness we have in the team this year, but we know where those weaknesses are and we just need to make sure that we improve upon those areas over the winter.
"But Force India have done a fantastic job ... they have just done a better job than we have and we need to look into that. We don’t want to finish fifth in the world championship. It’s a bit of a disappointment having come third in two consecutive seasons, in 2014 and 2015. We just need to do a better job."
Williams will have a different driver line-up in 2017 after Felipe Massa's retirement, with rookie Lance Stroll replacing the Brazilian. Valtteri Bottas' future is also uncertain as the Finn is a target of Mercedes to replace the retired Nico Rosberg.
Virtual reality: The future of F1 coverage?
Jorge Lorenzo: When a two-wheel champion tests a Mercedes
Silbermann says ... Ignore Flavio, get Alonso in
INTERVIEW: Stoffel Vandoorne: The long wait is over
Keep up to date with all the F1 news via Facebook and Twitter
In a race that will be etched in Formula 1 history, Mercedes sensation Kimi Antonelli…
There was deep frustration – and a sense of concern – inside the McLaren garage…
The 2026 Chinese Grand Prix delivered a historic changing of the guard as 19-year-old Kimi…
Full race results from the Chinese Grand Prix at Shanghai, round 2 of the 2026…
The Chinese Grand Prix was thrown into chaos before a single light turned green on…
Formula 1 has confirmed that next month’s races in the Middle East will not take…