When the article was written Federer had lost to Djokovic after having 2 match points on two seperate occsasions (US Open 2010 and 2011) and since then this has happened again at Wimbledon 2019. In that last two matches Federer was serving as well. It's hard to make the argument that this isn't psychological.
If we model tennis points as random (let's say, accounting only for service), would we not expect people to occasionally lose when they had a match point? We'd expect this to happen more often when playing an opponent of comparable skill.
It's not obvious to me that it's psychological at all, and it seems to me that it's only reported as such because it makes a good news story.
According the most recent of these threads Federer's lose-after-match-point percentage is 1.4%. Djokovic's is 0.2%. Djokovic also has a much higher win-after-facing-match-point percentage. It's hard to claim that this is purely due to randomness.
If you want to convince yourself that choking is a thing, then this is a stat you might look at.
But, this stat is just as likely to be more influenced by how close your opponent's skill was on that day (how often you play opponents at a similar skill level), your and your opponent's relative stamina, whether those match points appeared in a regular service game or a tiebreak (how often your style of play goes to a tiebreak), and perhaps even pure luck - out of thousands of tour players, some are going to have incredible luck.
djokovic was already an extremely strong (mentally, physically, and technically) player himself at that time. he finished the 2011 season no. 1 IIRC.
the "mental toughness" argument cuts both ways. pulling out a win after two match points in a grand slam speaks as much to djokovic's own mental fortitude as it does to federer's lack thereof.
To elaborate beyond what @soneca said, how do we know that Federer lost those points because he thought too much? What if, instead, Federer didn’t think enough, and Djokovic just outthought him? That’s why the conclusion is unfalsifiable.
For me is veeery easy to make the argument that this isn’t psychological, but only to the expected variance of tennis match results. It was you that had to carefully cherry-pick data to support your conclusion.
I would only have to choose among all the other match points he has won through the 20 grand slams he has won. Only considering Federer vs Djoko, Federer won 46% of the matches. There a lot of match points won there. Also, considering only Grand Slams, Federer won 6 out of 17. Not a great record, but still no negligible number of wins. And I would attribute that bad performance more to Djoko skills, and maybe also Djoko physical peak coinciding with Federer older age, than to any thing psychological.
