But in several cases this week, there was evidence that the sport’s white leaders and players were listening more. When the Los Angeles Dodgers’ Mookie Betts, the most prominent African-American player in M.L.B. and the only active one on his team, told his teammates that he didn’t want to play on Wednesday, the star Dodgers pitcher Clayton Kershaw, who is white, said the team discussed how they could support Betts. They ultimately decided to join him.

“We’ve been wearing these shirts throughout the year but there comes a time where you have to live it, you have to step up,” Brewers star outfielder Christian Yelich, who is white, told reporters on Wednesday while wearing a T-shirt that said “JUSTICE EQUALITY NOW.”

Such solidarity from white players is “1,000 percent” necessary to enact changes, said Edwin Jackson, a Black pitcher who played for 14 major-league teams over 17 years. In a phone interview, he commended the teams whose players had demonstrated together, regardless of ethnicity. “That speaks volumes instead of one person here or there doing it,” he said.

Jackson, 36, is on the board of directors of the Players Alliance, a nonprofit formed earlier this year made up of more than 100 former and current Black players. Before now, he said, Black players did not have a way of coordinating their initiatives across the league. On Thursday morning, he said players from the nonprofit met in a Zoom video call to formalize their plans to donate their game checks from Thursday and Friday to efforts that combat racial inequality and aid Black communities.

“We haven’t been able to talk in baseball in forever,” said Jackson, who last pitched for the Detroit Tigers last season. “This might be the first year where players can express how they feel. And you still have in the back of your mind that maybe there’s some backlash, but we are speaking. This is the most that I’ve ever seen anyone speak, especially Blacks and African-Americans, in baseball.”

When the M.L.B. season began in July, some players feared it would take attention away from the larger social justice movements exploding across the country. And when another Black person was shot by police this week, some players found it harder to focus on their job as entertainers.