In the precarious business of managing a baseball team, April really did turn out to be the cruelest month.

When the Kansas City Royals fired Tony Muser after Monday night’s game a 4-0 victory over Detroit he became the fourth manager to go down in the season’s first month, twice as many as ever before.

Usually owners exhibit at least a little more patience with their teams. The baseball season, after all, is a marathon, not a sprint. Two years ago, every manager made it through the season intact, the first time that had happened since 1942.

But all that changed this year with Muser joining Colorado’s Buddy Bell, Milwaukee’s Davey Lopes, and Detroit’s Phil Garner as dugout casualties before the calendar reached May.

And that doesn’t include Boston’s Joe Kerrigan, who never made it out of spring training, fired as soon as the sale of the Red Sox was finalized.

Muser was matter-of-fact about his dismissal.

“Everybody understands the circumstances, the mood of our fans,” he said. “They need a change. It’s just a part of this business. Managers are hired to be fired. I understand it, and life goes on. The most important thing is the success of the organization.”

Each of the fired managers had three things in common. They had been on the job for a while, their teams were struggling, and home attendance had dropped.

The first two are significant. The third might be fatal.

“The real point is attendance,” said Chuck Tanner, who managed both Garner and Muser during their playing careers. “They always look at that.”

Bottom-line baseball craves customers, and the four teams that fired managers have seen average attendance slip nearly 2,000 a game in Detroit, almost 8,000 a game in Milwaukee.

Then there are salaries. Colorado had the highest opening-day payroll of the four at almost $57 million. That’s 19th highest in the majors, less than half the $126 million George Steinbrenner pays the New York Yankees.

“I understand,” Tanner said. “Kansas City, Detroit, Milwaukee, Minnesota, they want to win the World Series just like New York. New York wins with $100 million payroll. They want to win with a $50 million payroll. It can’t happen.”

Tanner managed for 19 seasons and was fired three times and traded once by quirky owner Charles O. Finley in Oakland. His last dismissal by the Atlanta Braves came after just 39 games.

“We had just beat the Pirates with Tom Glavine,” he said. “I was thinking now we’re coming on. I knew we had these kids in the system. I knew we were coming. We went into Chicago and they said ‘We’re making a change.’ “

The Braves finished last that year and the next two without Tanner before embarking on a 10-year streak of winning their division.

Firing the manager is a statement by management that the team is not standing still, that it will turn around a bad start. It is often nothing more than cosmetic.

“I don’t understand how they can fire a guy so early,” Tanner said. “You’ll always have a time when you struggle. Sometimes they say, ‘We’re changing this guy because he’s too easy going or because he’s too hard.’ If you don’t win and you don’t draw, those are the biggest reasons.

“Look at Bell. First, his team was going to win with power. It didn’t win. Then they were going to win with pitching and defense. That didn’t work. Then they were going to be more aggressive. That didn’t work, either.

“Maybe, it’s the players.”

Now there’s a thought.

Tanner said he talked with Garner after the Tigers’ new president, Dave Dombrowski, fired him.

“It’s a new organization,” Tanner said. “They were going to make a change the first time something went bad. It’s their prerogative.”

Like his old boss, Muser was fired after his team won a game. Tanner laughed at that.

“Imagine,” he said, “what would have happened if they had lost.”