"In general, the Chinese are coming through where they notoriously used to crack under pressure," Brownell said.
Olympic rowing has 14 medals up for grabs, including Zhang's single and double sculls events.
This isn't the first time an Olympian has missed a competition. "Historically, this happens and it's easier than you might think," Brownell said.
At the 1972 Munich summer Olympics, American Rey Robinson was favored to win a gold medal in the 100-meter dash. His coach told him his quarterfinal heat was slated for the evening when, according to another schedule, his heat was in the afternoon. Robinson missed the race and was disqualified from the Games.
Other athletes have missed races on purpose out of fear that they will test positive for doping. Brownell, a longtime sports expert, listed myriad of possibilities.
"They want to avoid starting because they know they're going to get tested," she said. "Normally, [worried athletes] claim they're injured or false start or have food poisoning."
China's national team has not commented on the rowing absence, continuing to accumulate gold medals in other events including women's team gymnastics and diving today.
But what if winning the gold medal count for China comes down to one gold medal?
Brownell worries for Zhang: "The man would be a villain the rest of his life."
Zhantao Yang contributed research to this story.