The loss of key technical staff in 2013 was the main reason why Lotus's '14 Formula 1 campaign was so bad, believes trackside operations chief Alan Permane.
Technical director James Allison left Lotus for Ferrari before last season, with head of aerodynamics Dirk de Beer following him and other staff also departing.
Lotus went from being a grand prix winner in 2013 to struggling to get out of Q1 at times last year, scoring only three times and plunging from fourth to eighth in the constructors' championship.
"We had a fairly torrid winter last winter and we lost quite a lot of people, and the aero department was heavily restructured," Permane told AUTOSPORT.
"With all respect to [new technical director] Nick [Chester], James was an absolute team leader.
"Losing James was a big hit. We lost Dirk, our head of aerodynamics. We lost our head of CFD.
"These are all good people. No one can't be replaced, but it takes time when you get replacements in for them to start gelling.
"The previous aero department had worked together for five or six years and were churning out really good stuff. To stop that abruptly upsets things.
"But we have a great windtunnel and a great base at Enstone. There's no reason why we won't get back on the right path again."
PROBLEMS COULDN'T BE FIXED IN 2014
Permane said Lotus soon realised where its E22 was flawed, but the problems could not be fully fixed until the 2015 design.
"There are three or four things that make cars quick, and one of them is aero - and it's not strong enough [on the 2014 car], it really isn't," he said.
"But we're pretty sure we know where it isn't, and it wasn't something that could be changed on that car.
"We have changed it on next year's  car and we can already see very significant gains in the windtunnel. So we're very confident.
"While we're not going to say we're going to go out and beat Mercedes and Red Bull - those teams that are employing almost double the people we're employing - we're very confident that we'll be regularly back into Q3 and fighting for podiums again."
He also believes Lotus managed to learn from its 2014 troubles.
"We've learned a lot. We didn't have a great year when we did our side exhaust [in 2011], but we learned a lot about exhaust blowing and that helped us in the following years," Permane said.
"There's no doubt that in the last three or four races the car markedly improved.
"It didn't really improve position-wise because we had such a big gap. But if you look at the percentages from pole position, we closed things up."