The Call ‘Play Ball’ Will Not Say it All : Opening day: They will be mourning in Cleveland, protesting in Baltimore and rooting for a new team in Colorado.

It’s time to get serious about baseball.

Another opening day is here and, as usual, there are a few new twists.

There are the new faces--about 250 players changed teams during the off-season. There are two new teams in two new cities, where fans have embraced the game in grand fashion. In another city, a new president will throw out the ceremonial first pitch.

But not everybody will be celebrating.

The mood will be somber in Cleveland when the Indians play the New York Yankees.

Manager Mike Hargrove and General Manager John Hart will present the jerseys of pitchers Steve Olin and Tim Crews to their widows and parents. Olin and Crews were killed March 22 in a boating accident that also injured Bob Ojeda, who starts the season on the disabled list with scalp injuries.

In Baltimore, where President Clinton will throw out the first pitch before the game between the Orioles and Texas Rangers, the Rev. Jesse Jackson will be outside leading one of a series of protests against the major leagues’ lack of minority hiring.

But as far as baseball fans are concerned, it’s time to play ball.

In Colorado, the Rockies begin their first major league season against the Mets in New York. In Florida, the Marlins open their first season against the Dodgers.

At Wrigley Field, Greg Maddux will be on the mound when the Cubs play host to Atlanta, but Maddux, who won the Cy Young Award last season with the Cubs, will be pitching for the Braves.

Maddux turned down a $25-million offer by the Cubs and signed for $3 million more with Atlanta.

In Cincinnati, Tony Perez will start his career as a manager in the Reds’ game against the Montreal Expos, and at Houston the Astros will play host to Philadelphia.

In other American League games, Boston is at Kansas City and Detroit is at Oakland.