For a mixed medley relay race, why is it a disadvantage to have a woman swim the second (breaststroke) leg and a man swim the anchor (freestyle) leg?

Question

On the NBC live broadcast of the Mixed 4x100m Medley Relay swimming event of the 2024 Summer Olympics, commentator Rowdy Gaines said that it is ideal for men to swim the first 2 legs (backstroke and breaststroke) and women to swim the last 2 legs (butterfly and freestyle).

Looking at the results of the race, 4 of the countries used a MMWW order, and the other 4 countries used a WMMW order. That means all the countries decided to have a man swim the second leg (breaststroke) and a woman swim the anchor leg (freestyle).

Also, looking at the results of the mixed 4x100m medley race at the 2020 Summer Olympics (the Olympic debut of the event), 7 out of the 8 countries used either a MMWW or WMMW order. The United States used a MWWM order and finished in 5th place. The Wikipedia article blames the United States' failure to medal on the MWWM order:

Opting against tradition by using a female breaststroker, the decision backfired massively for the U.S. as they were left off the podium for only the second time in an entered relay event in Olympic swimming history

Why is it a disadvantage to have a woman swim the second (breaststroke) leg and a man swim the anchor (freestyle) leg in a mixed medley relay race?

Answer 1

It would seem that the differences between men and women swimmers is not roughly constant for the various strokes. For example, comparing the current World Record for the 4x100m relay for all men or all women:

• Backstroke M faster than W by 4.97 seconds
• Breaststroke M faster than W by 6.41 seconds
• Butterfly M faster than W by 6 seconds
• Freestyle M faster than W by 5.47 seconds

Obviously, this is comparing one WR race to another, but would seem that if this is representative, you'd want to swim WMMW, and want to avoid W swimming the breaststroke.

To expand, if you take the average of the last three WRs for M and W set in each stroke, you see again:

• Backstroke M faster than W by 5.54 seconds
• Breaststroke M faster than W by 7.27 seconds
• Butterfly M faster than W by 5.84 seconds
• Freestyle M faster than W by 5.26 seconds

(times taken from Wikipedia: Backstroke, Breaststroke, Butterfly, & Freestyle) Now, just averaging the last 3 WRs set in each likely has some biases, but we again see that men seem to have the largest time advantage over women in the Breaststroke -- so it seems like WMMW or MMWW, or even WMWM are more reasonable.