A year is an eternity in Formula 1, and thus plenty of time to plummet from hero to zero.
At the end of the 2013 F1 season Renault was riding high. The French manufacturer had just won its fourth consecutive world championship double with Red Bull, plus 44 wins, 115 podiums and 53 pole positions across a spread of just 77 races as an engine supplier.
That's a success rate of 57 per cent over four seasons in terms of wins, and a phenomenal 69 per cent in terms of pole positions. In 2014, Renault won just three times (a 16 per cent success rate), and not once did its engine power a car to pole...
Fans will recall the disastrous pre-season images of Red Bull-Renaults regularly breaking down in clouds of white smoke. Considering its late start with F1's new hybrid V6 turbo formula, and the initial performance and reliability deficit to standard-setter Mercedes, the season that followed represented a remarkable turnaround for everyone at Renault's Viry base.
Taffin often had to explain Renault failures early in 2014 © XPB
But this is not why Renault is in F1. Like everyone else, Renault is in F1 to win. In that respect, 2014 was a failure.
In fairness, it made gains on Mercedes as the year progressed, but Red Bull never missed an opportunity to point out the failings of its power unit, and Renault knows it still has a lot to do over the winter to try to make up the deficit.
"All in all, it was a bit difficult because we still had some problems, but they were linked to the fact that we were still using parts from the beginning, so it does not really show off the steps we have taken," Renault's head of track operations, Remi Taffin, tells AUTOSPORT.
"If you look at the last five races, the units we put into our cars were definitely a step. There are a few things we need to do reliability wise, but I think we learned quite a lot and we should be able to make a good start this season."
Even so, Taffin is under no illusions that Renault will be able to overturn Mercedes' advantage, and makes the unusual admission that he'll settle for making the shortcomings small enough for Red Bull and its drivers to perform more frequent magic.
"I think it would be even more than optimistic to say we will be ahead of Mercedes, but we will try to close the gap as much as we can.
"Eventually, instead of being more than a few per cent behind, we think we can be just one or two per cent behind.
"Within this range, we know that a driver or chassis can make up the difference and that's the target. When you are within range, you can make up things in other ways."
BACK TO BASICS
Red Bull went from dominating to chasing Mercedes in vain © LAT
Naturally, much of the focus ahead of the season was trained on the hybrid elements used to recover and redeploy waste energy from the brakes and turbos.
As the new-fangled part of F1's current engine packages, many would assume this is the area to focus on if you want to beat Mercedes.
But Taffin argues Renault's gains are more likely to come from the old fashioned part - the Internal Combustion Engine (ICE) - in a formula that is now principally about burning a limited amount of fuel (100kg) in the most efficient way possible.
"We have a lot to do on the ICE," Taffin admits. "What you have on the car now is 100kg of fuel, while you have four megajoules of electricity, which is nearly nothing in comparison to the 100kg of fuel.
"You have to burn that fuel the most efficient way, and what is burning this? The ICE. Performance will come from the efficiency of the fuel, the efficiency of the ICE, and how you use it.
"If you think early on, 'what's going to be the master thing in the power unit?' everyone will say 'ERS, ERS, ERS'. We knew that everything was important, but ERS was the newer thing, so you would probably pay more attention to that aspect.
"It's natural, as we've always been doing the ICE. In complete fairness, we've perhaps underestimated that part."
Red Bull's top brass made their feelings clear to Renault © LAT
Renault has responded to pressure from its number-one customer Red Bull by pledging to focus exclusively on the Milton Keynes squad as a 'works' partner in 2015, and that closer relationship will work in both directions.
"It will help for sure, but it's not going to be easy," says Taffin.
"It's fair to say that the closer partnership with Red Bull is technically very interesting as they have a lot of intelligent engineering people, and many people in Milton Keynes who can help us in many areas.
"When we talk about aero, we don't mean aero on the car, but the aero in an combustion engine, so they can definitely help us, though it's fair to say that designing a chassis is not the same as an engine."
Red Bull continued to play politics over rules that limit the amount of engine development that can be done (unsurprising given the size of its fall from grace this year), and received a Christmas present when the FIA acknowledged that a rules loophole meant there was no pre-season deadline for the permitted upgrades. That greater leeway certainly won't hurt Renault.
In the meantime, all Renault could do was crack on with its to-do list. A return to the top is unlikely to happen overnight given the size of Mercedes' advantage - and the fact the Silver Arrows will be working hard to improve over the winter.
But Renault and Red Bull have been winners before, and winners don't like losing. Losing usually means they come back harder, and stronger. Watch this space.