Toro Rosso technical director James Key believes his former team Sauber has "all the fundamentals" necessary to bounce back from its difficult start to the 2014 Formula 1 season.
Key worked at Sauber from 2010-12, before replacing Giorgio Ascanelli as Toro Rosso's technical director.
The Briton, who left Hinwil amid frustration at not having the necessary budget to move the team forward, said Sauber still has the right facilities and personnel to be successful, despite failing to score a point thus far with its difficult C33 design.
"It's a very complicated season and these cars are hugely different to last year," Key told AUTOSPORT.
"I left [Sauber] about three months before the initial project was started to understand how the regulations would work, so what happened after that I honestly don't know.
"They do seem to have had some struggles and have also had reliability issues as well, which probably hasn't helped.
"I think it shows how difficult it is, to be honest."
Key believes the legacy of Sauber's days as BMW's factory F1 team give it a better chance of recovery than other struggling squads.
"The facilities there are fantastic, it's obviously about making use of those facilities as best you can within the restrictions we have now with budget levels and so on.
"I don't know what their budget is, but from a facility point of view it's very strong and there are some really good people there as well.
"I always viewed it as a team where all the fundamentals are there with the investment from BMW previously, it's just a case of getting it to work I guess."