Is 2017 Federer that Different than 2015 Federer?

With just one Grand Slam remaining in the 2017 season, it is already clear that one of the biggest stories of the year will be the renaissance of Roger Federer and Rafael Nadal’s dominance.

This year has been an especially standout season for Federer who has won every Grand Slam and Masters event he has entered so far. The last time Federer has had a comparably pristine record thru Wimbledon was in 2004 and 2005: two of the strongest seasons in his career to date.

Unsurprisingly, the results we have seen in 2017 are leading many to call this a vintage year for the Swiss star. An equal number have spent much of the season looking for the answer to how Federer seems to have gotten a new lease on an already enviable game.

It is tempting to look at Federer’s selective schedule and unflappably serene temperament this year and give them the lion’s share of the credit for his 2017 achievements. But that would ignore a fundamental piece of any player’s record—the strength of his competition.

Is Federer’s success this year a sign that he has refined his game? Or has he rather maintained his level when other top players have faltered and when none of the next generation have risen up to challenge the old guard?

Debating over these questions kept bringing me back to 2015. In that year, at both Wimbledon and the US Open, Federer eased into the finals and seemed poised to end his Grand Slam title drought only to be thwarted by Novak Djokovic at every turn. We didn’t know it then, but in 2015 Djokovic was building up such an impressive run of wins that by early 2016 he would reach the highest peak all-surface Elo that has yet to be recorded in the men’s game (+2543).

While the difference in Federer’s form between 2015 and 2017 is open to debate, there is no question that 2017 Djokovic has been just a shadow of the player he was in 2015. And once that point is made, it leads us to inevitably ask how much Federer’s success in 2017 is thanks to Djokovic’s slump?

Put another way, has Federer had to go up against any opponent in 2017 who was as formidable as Djokovic in 2015?

The above chart tries to answer this question by contrasting the Elo ratings of Federer’s 2017 and 2015 opponents at the time of their matches for all completed matches at the Masters or Majors thru Wimbledon. The orange horizontal line shows the strongest opponent in 2015 according to Elo (who happens to be Rafael Nadal). We can see that the line is well below Novak Djokovic’s level when he handed out three losses to Federer at the 2015 Indian Wells Masters, Rome Masters, and the Wimbledon Championships.

Interestingly, the max strength of opponents in 2017 is also slightly less than the strength Andy Murray was playing at when Federer beat him in the semifinals of the 2015 Wimbledon Championships.

On the other hand, Federer also had loses to opponents in 2015 that were comparable in strength to opponents he defeated in 2017. However, three of those four losses were during the clay court season, which he entirely skipped in 2017, perhaps in part on the basis of those 2015 trends. That just leaves the loss to Andreas Seppi in 2015 as a bit of an outlier.

By and large, I think this makes a strong case that Federer hasn’t radically reinvented himself in 2017, as some of the tennis commentary would seem to suggest. Instead, he has been able to play at his 2015 level— an amazing achievement in itself— while other (and younger) players at the top haven’t managed the same consistency.