After an exceptionally bleak start to 2013 by his standards, much was expected of Roger Federer at Wimbledon. After all, he was the defending champion, and this was his lawn.

But in a career-low performance, he lost to world No 116 Sergiy Stakhovsky in the second round. This was his earliest exit from Wimbledon in a decade and from a Grand Slam since 2004. As the 2013 tour progressed, a back injury plagued him and he didn’t make a single Slam final. In fact, he reached only three finals in the entire year, winning just one at Halle against Mikhail Youzhny. In the legendary play that is Federer’s career, 2013 was the falling action.

But as is expected of great champions, rather than succumbing to the situation, Federer faced it. He realised he had to change things to protect the longevity of his career. So he did something he had not done before: he changed his racket, switching from a 90-square inch frame to a 97-square inch one. He also changed his team, parting ways with Paul Annacone and bringing in in tennis legend and one of his personal idols, Stefan Edberg, in January 2014. Little did anyone know then that in making these changes, Federer had paved the way for career re-defining season, which came in 2017.

The gear and personnel changes strengthened a part of Federer’s game that had long been targeted by his opponents – his backhand. The larger frame of the new racket allowed for a bigger sweet spot and thus, more power was on tap. Although this did not begin paying dividends in terms of titles immediately, it was evident that there was a new freedom with which the former world No 1 was hitting his backhands.

Consider this chart of how frequently his opponents would serve to his backhand as compared to his forehand at Grand Slams:

The big gaps during the initial years between the orange and the blue lines is evidence of opponents targeting his backhand much more often on serve. But Federer’s improved backhand seems to have affected the way his opponents are serving to him and we notice the gap between the lines closing in recent years. The difference is even starker if we only consider matches against his biggest rival, Rafael Nadal.

In the 2004-2013 period, Nadal was sometimes serving as much as 90% to Federer’s (then much weaker) backhand. But right around 2014, when Federer changed his racket and team, we see a Nadal shifting to the 60%-80% belt and dropping further in 2017. At the Miami Open final this year, he current world No 1 served almost equally to both sides, for the first time.

Nadal’s example shows how Federer’s improved backhand is affecting his game plan. He is becoming wary of the Swiss being able to attack with it. And if Nadal, who leads 23-15 in his head to head against Federer, is having to change his tactics, it would only be fair to say that other players would be facing the same dilemma too.

But having a powerful shot is no use if you’re not comfortable hitting it. It seems like one of the 2017 goals for Federer has also been to address a long-term chink in his style of play: his overuse of the defensive backhand slice. In an earlier interview, he said that even his father had been frustrated by this: “He’s the first to tell me, ‘Hit the backhand, dammnit. Don’t just fall back and slice all the time”

But a look at the ratio of Federer hitting a backhand to a slice in matches shows that even this handicap has been addressed this year.

Immediately, we notice a downward spike in the slice pecerntage in 2017 (and simultaneously, an upward spike in backhands). He has overcome the difficulty of attacking consistently with a one-handed backhand. After his win against Nadal in the final at Shanghai Masters in October, Federer himself explained how the bigger frame has helped him use the backhand more:

“Before I had to slice more just because the racquet was good for the slice, and it was good for the coming over, but I would always shank too many balls. I think it was hard for me to consistently just keep on attacking with the backhand. Today it seems almost not a problem anymore to do it.”

Looking at the numbers so far, it seems like Federer has converted a long-term weakness in his game to a strength he can readily attack with. But to be able to attack with a shot is not as important as being able to depend on it crucial moments. And in tennis, breakpoints are as crucial as any, often deciding entire matches.

Looking at Federer’s breakpoint stats, there has been a change in that as well. The following chart shows how often Federer is winning when attempting a backhand winner while facing a breakpoint or attempting to break his opponent’s serve.

Since 2014, when he made the changes in his game, there is a continuous increase in the percentage of winning backhands on breakpoints. To give an example of how large these improvements have been, consider this: in 2014, Federer won 18% of break points where he tried to hit a backhand winner. In 2016, that number was up to 35% and reached 55% in 2017.

This can be a combined result of the racket change, Edberg’s two years of guidance from 2014-2015 and hiring of Ivan Ljubicic as his coach in 2016. While Edberg knew aggressive tennis of the serve and volley age, Ljubicic knows weaknesses in Federer’s and his opponents’ games having played against them many times. And with his bigger Wilson wand, Federer is free to hit with more power as well.

All these changes have paid amazing dividends in 2017, with Federer and his backhand’s resurgence being the highlight of the tennis calendar. After taking an unprecedented break of six months in the second half of 2016 to recover from injury, he came back to win the Australian Open beating Nadal in the final. He also came back to own the grass and won a record-breaking eighth Wimbledon title without dropping a set in the entire tournament. Not to mention the 4-0 record against Nadal this year.

Federer’s seven titles this year with a win-loss record of 52-5 – his best in terms of win percentage since 2006 – can not only be attributed to his being back to full fitness, but also to the fact that he has managed to convert his one biggest weakness into a weapon.

But the most important factor for Federer’s resurgence cannot be quantified: his will. After the relatively dismal year in 2013, everyone had begun writing him out. Questions about retirement were frequent in press conferences and even though his game was improving, the titles were few and no one expected a renaissance like 2017.

However, the Swiss maestro perhaps did, as he steadily worked on his biggest weakness in the twilight of his career. If Federer’s current form continues, it seems like tennis’s greatest tale might get the finale it deserves.