Ratings and the Olympiad

In an earlier article (Are 2700s Overrated? Insights From the New Model), I showed that 2700s underperform when they face weaker opponents. For example, a 2750 is expected to score 70% against a 2600. This comes from Elo's formula. However, in the data, he is only scoring about 65%. Thus, if a 2750 plays 11 games against 2600s, he will probably lose 5.5 rating points (i.e. 5% per game multiplied by 11 games multiplied by a K factor of 10). So we would expect members of the 2700 club to shed points in the Olympiad. Here is how they did:

Carlsen -3

So -2

Giri +4.3

Aronian -16.4

Caruana -18.3

Mamedyarov -0.5

Dominguez -9.4

Duda -9.1

Harikrishna -3.8

Maghsoodloo +11.9

Shankland -7.5

Vallejo +0.8

Vidit -3.7

Wojtaszek -14.8

(Data from 2700chess.com)

With a few exceptions, their ratings fell. However, it was especially bad for Team USA. "2700s tend to be overrated" doesn't fully explain their performance. Some other factor must be at work.