SEOUL, South Korea — The Major League Baseball commissioner, Rob Manfred, said that the World Baseball Classic was here to stay, and that despite criticism that some of the world’s best players are sitting out the tournament, the teams had never been better.

“The U.S. position players, their roster is pretty darn strong,” Manfred said in an interview before the tournament opened on Monday with Israel beating host South Korea, 2-1. “You’re never, ever going to have every guy. There’s going to be some guys who are injured, guys who don’t want to play for some reason.”

As in the past three installments of the tournament dating to 2006, some of the best players have not taken part. Mets pitcher Noah Syndergaard was among the many elite players who opted not to join the tournament, instead focusing on preparing for the season with his club. Bryce Harper, Madison Bumgarner and other top stars also opted not to play for the United States.

Manfred said that scheduling was one of the biggest challenges facing the tournament. The players must be in good shape, which means moving the tournament up to February is impractical. The distance that some players must travel, including to Asia, makes it difficult to expand the event beyond its 16-team format. Teams could be added, but probably through more qualifying rounds. But even those games would require players on minor league and major league rosters.