The decline of the Cincinnati Reds' baseball empire was dramatically documented yesterday when Manager Sparky Anderson was unexpectedly fired and replaced by John McNamara.

"I'm totally shocked," said Anderson, whose candor and self-deprecating wit were the heart of the bludgeoning Big Red Machine that won back-to-back world series just two years ago.

"I never knew this was coming," said Anderson, whose managerial sin was finishing second to Los Angeles that last two seasons. "I guess maybe I'm not smart enough to figure it out."

A shock to match Anderson's dismissal was Cincinnati's choice of successor - the much-traveled McNamara. If the Reds had searched all of baseball they could hardly have chosen a manager so similar to Anderson in personality and style, yet so opposite in results.

"I'm flabbergasted," said McNamara, former Oakland and San Diego manager who coached for California last season. "Just 24 hours ago, I was in the Dominican Republic pitching batting practice to Manny Mota."

McNamara, who describes himself as "low-key, loyal to the organization . . . a lot like Sparky," has a 321-388 career record. Anderson's career mark was 863-586 (.596), the second-best record in modern times.

Only one question about Anderson's firing remained unanswered yesterday: Why?

The Red's explanations were deliberately vague, with General Manager Dick Wagner finally saying, "We are simply not going to expand on our formal statement. It's time to make a change . . . the past two seasons have been good ones for most clubs, but we are determined to meet a higher standard . . . the situation today calls for a new approach."

"I will not under any condition discuss what happened," said Anderson, referring to the background of his firing.

"Managing the Reds changed my life more than anything ever did," said Anderson who often referred to himself as "a career bush-leaguer who got to sit on the bench and watch a great team play."

"I'm not a crying type of person," added Anderson. "I respect the Reds' decision that I'll always respect them for at least sitting down with me."

That final sitdown, however, stunned Anderson. Wagner flew to Los Angeles (Anderson's home) on Monday, summoned the manager to a motel room at Los Angeles International Airport, then told him in a two-hour meeting that he was fired.

"Sparky is taking it well," said his wife, Carol. "He's composed on the outside, but it was a complete shock. The team just got back from a tour of Japan on the day before Thanksgiving. All the club officials went along. There were no problems. The team won the last 12 games in a row."

"I came to the Reds with my honor and I want to leave with it," said the gregarious Anderson, who was remarkably honest by the normally surreptitious standards of baseball managers. "The game is bigger than anything else.

"It's funny. I feel a little bit now like I did when I was hired . . . a strange tingling sensation.

"For now, I'm going to relax. I have another year to run on my (Reds) contract . . . I hope I have made a big enough impression on the game of baseball that somebody will come calling for me. Until then, I'm gonna enjoy the old golf course."

Anderson was a bit more realistic, and a bit less humble, when he faced a Red slump in August by saying, "I could pick up the phone and have a job in five minutes."

In baseball's world of musical managers, Anderson's past performances, charm and company-man image will surely allow him to take his pick of jobs as they become available. Fans in talent-rich but titleless Philadelphia and Boston are particularly likely to send him cards for Christmas.

Of more long-range interest in the plight of the Reds, the club that was being compared with the '27 Yankees only two Octobers ago.

While Anderson was taking his canning with good grace, Red star Pete Rose continued his week-long, coast-to-coast tour of teams that want to bid for his free-agent services. "All negotiations have broken off with Pete," said a Red official. "He's just flying from city to city to see who'll offer him the most cash."

Wagner denies that Anderson's and Rose's fates are linked. "This wasn't a hurried decision," said Wagner. "I've thought about it since August."

August was when Red catcher John Bench said, "Our manager is too low key . . . I wouldn't exactly say he is intimidated by our (rich) stars, but it's close . . . Sparky has withdrawn from it all."

Rose's defection may have catalyzed Anderson's firing as much as Bench's words. Rose was Anderson's favorite player, his teacher by example, his light-a-fire-under-'em tool.

Without Rose, Anderson's lack of stearnness might have been even more visible. When a Red needed a tongue-lashing, it was Rose, not Anderson, who usually supplied it.

Anderson also believed in the past lineup the Big Eight, "my coconuts" as he called his regulars. Rose's departure would be the first cracked coconut, a loss that might force the Reds to trade others stars. Joe Morgan's name is already prominent in trade rumors.

A rebuilt Big Red Machine, with youthful spare parts and few Hall of Famers in the locker room, might be as well off without a manager who encouraged a star system.

"I never embarass my coconuts," Anderson always said. "I never forget that they're the ones who have made me so smart."

Whatever the unspoken reasons, the Feds have contributed a page to the improbable lore of managing. Anderson finished only 2 1/2 games out of first place this season with a team that made 39 more errors and scored 92 fewer runs than it had the year before.

Among friends, Anderson said that this was probably his best season as a manager. With the ninth-best pitching in the league, with less offense and less defense, he skippered the Reds to 92 wins, four more than they had in '77.

Yet the man whose career winning percentage is second only to Joe McCarthy found himself out of work yesterday.

Appropriately, Sparky Anderson stepped down with style - the first manager to be fired with his team on a 12-game winning streak.