Those who fretted about baseball just a few years ago have a problem now on the eve of Spring Training '79.

They can't find anything momentous about which to worry. Seldom, if ever, has the state of baseball been so strong.

The sport that prides itself on tradition and continuity, the game that Teddy Roosevelt, if he could return to earth tomorrow, would understand, may have been through the most dramatic revolution in its history over the last four to five years.

Not long ago, baseball folks thought they were about to be crushed under a free-agent free-for-all, massive labor problems and litigation, declining attendance and sagging TV ratings, a moribund American League and an entire game dominated by aging stars.

Now, for a number of reasons, baseball, with its soaring attendance (40,636,886 in 1978) and growing television ratings, can snicker at the doomsayers.

The labor-and-law nightmares turned into a bonanza of free-agent publicity and fan excitement, making an unprecedented number of teams interesting.

Of the 50 all-stars in the spring of 1974, four have retired, 13 have remained with the same team and a staggering 33 have changed teams. Some of those 33 have played for as many as five teams in five years.

The American League, which now has more 90-win contenders in the East (four) than it once had in the whole league, is bristling with young stars. But then the National League is in the midst of a baby boom, too.

Ever since New Year's 1975 when Catfish Hunter became the first multimillion-dollar free agent, baseball has lived a charmed life. For four years, its run of luck has held.

From Hank Aaron's 715th homer to Lou Brock's 118th stolen base, from more Astro Turf fields to the new Rawlings ball, from Carlton Fisk's foul-pole home run in '75 to "Reggie-Reggie-Reggie," everything baseball has touched has turned to gold.

Just when the old gal seemed to have lost her vitality, along came the greatest of Big Red Machines and George Steinbrenner's rudderless Ship of Fools to win back-to-back world titles each.

Baseball is once more stocked with high-profile stars and teams with clear identities.

In the fundamental categories, baseball again has stars who stand up superbly to a century of comparison.

Hustler: Pete Rose. Showman: Reggie Jackson. Pure Hitter: Rod Carew. Pitcher in Prime: Ron Guidry. Potential Unlimited: Jim Rice. 300-Win Pitchers: Jim Palmer and Tom Seaver, en route. Triple Crown Adversaries: George Foster and Dave Parker.

Teams like the Yanks, Red Sox, Dodgers, Phillies, Reds, and Royals bring lineups that are familiar top to bottom and reputations as psychologically engrossing as a Russian novel. In addition never have so many teams considered themselves genuine contenders -- 13 teams were at least 10 games over.500 in '78.

To appreciate baseball's health today, it is useful to look at the dramatically different game of just five years ago. What was baseball like before spring training of 1974?

In those days, few seriously thought that free agents might become a reality. The concept of total bargaining freedom was chimerical labor bargaining tool -- a beastly threat made idly and rebuffed easily for more than 60 years.

The idea of a Free Agents Sweepstakes in November -- a month of public auction -- was unthinkable. Even players said that baseball without a reserve clause would be chaos.

In those days, Aaron, holding all winter at No. 713, earned a kingly $200,000. The thought of a million-dollar annual salary was something for the 21st century.

The 40 years from Ruth to Aaron had raised top salaries threefold. The next five years would raise them fivefold.

Only five years ago, baseball had never hired a black manager -- let alone fired one -- and the designated hitter rule was only one year old.

The speed boom, unleased by Brock, was undreamed. That the Oakland A's could steal 341 bases would have sounded psychedelic. In a twinkling, the distance between bases, which had seemed so constant for so long, suddenly began to shrink.

The power explosion of '77, ignited by the new "Rawlings Rabbit" was an even more remote notion. Foster's 52 homers and Rice's 406 total bases would have seemed like a publicist's fantasy in '74 when the AL had no one with more than 32 homers or 287 bases.

No one suspected -- and some still don't know -- that by 1978, baseball would have its best balance of power, speed, scoring and pitching in history. A sort of statistical balance of power was reached between all the basic statistics of the game -- an unprecedented situation.

Nonetheless, the most staggering and important difference between baseball then and now is the most obvious difference: free agentry.

A few simple charts show how baseball has been more transformed in recent years than in any other period in the game's history.

A sport's identity is its stars, not its rank and file.

So, running with this story is a chart of the 25 best players in the American and National leagues before the 1974 season and before the 1979 season, based on the previous season's statistics and a general, common-sense evaluation of players. Although these hypothetical all-star teams are subjective, the same conclusions would be reached with any sensible selection of stars.

Where are the "best" of five years ago today, and where were today's stars back then? The answers to both questions are almost equally surprising, and revealing.

First, we need a bit of historical perspective for comparison.

Throughout this century, it has been a baseball rule of thumb that star players, especially in their prime, are seldom traded, at least until they begin to age.

From 1954 to 1959, for instance, more than twice as many stars stayed with their teams as changed uniforms -- based on our subjective picks of allstars in both leagues.

From 1924 to 1929, much the same is the case, although the ratio is closer to 3 to 2 in favor of "stay" over "go."

In the last five years, that generations-old sense of stability and slow change in baseball was blasted to smithereens.

The 33 who switched sides since '74 are not fringe players in this 33-to-13 ratio -- these are the honchos.

In this new era of constant player movement -- especially in the first two sweepstakes years when all players were theoretically freed from bondage -- baseball has had two great allies: luck and the oft-maligned Bowie Kuhn.

A few theorists had argued for years that in a totally open market a quality player would be worth more to a poor team than he would to a good one. A "name" athlete would mean more in victories and attendance to a struggling Cleveland, Milwaukee, San Diego or Atlanta -- where his influence would be dramatically felt -- than to a team which was simply replacing a solid player with a slightly better one.

These theorists -- a tiny minority for 50 years -- apparently were proved right. Enough downtrodden clubs won in the million-dollar bidding so that the overall effect of free agentry has been to spread the player wealth, create interest in depressed cities, and actually promote more balanced competition.

However, on a one-time-only basis, it didn't absolutely have to work out this way. Certainly, the rich could have gotten far richer had a few owners of losing teams guarded their checkbooks. That's where the luck comes in. Bosses in Atlanta, San Diego, Cleveland, etc., opened their wallets, not following the example of the second-division tightwads like the New York Mets.

Baseball's biggest break in these whirlwind years, however, may have been Commissioner Kuhn, who finally came of age at the right moment. His emergence from phantom lawyer to a powerful position as arbiter of all he surveys came at a time when baseball needed a hand at the wheel that would take command.

In mid-1975, Kuhn's job was as shaky as the state of his sport. At the summer meetings, Kuhn needed allnight arm-twisting meetings to save his job from severe jeopardy and secure himself a new seven-year contract from the surly owners.

Kuhn seemed deeply shaken, calling the backroom politics to save his commissionership "obscene." From that day on, it has been obvious that Kuhn decided to use the security of his $1,225,000 contract to wield power as he saw fit.

Behind the court-approved shield of his mandate to act "in the best interests of baseball," Kuhn has shocked the owners who hired him by doing exactly that -- pursuing the game's interests, not just theirs.

It now appears that most of Kuhn's decisions in the free agent era -- whatever their philosophical or ethical value may be -- have been dramatically effective in boosting the game at the practical level.

In almost every instance, Kuhn has seemed to ask himself what the typical disinterested fan would want him to do. When rich teams like New York and Boston tried to make phony trades that were really straight million-dollar cash buys, Kuhn did not resort to logic-chopping or semantics.

In effect, he said, "You rich guys aren't playing fair, and I'm not going to let you do it."

In an era obsessed with establishing the most picayune legalistic rights -- whether they make sense or not -- Kuhn was generally ridiculed as a meddling handicapper. "What about poor (owner) Charlie Finley's rights?" the critics cried.

Rivaling Kuhn's growth as a commissioner of confidence and some common sense is another of those uncontrollable factors that demonstrate baseball's uncanny good fortune.

In recent seasons, baseball has hit one of its periodic but unpredictable gushers of young talent.

That's what the second chart of current all-star picks illustrates.

Of the 50 top stars in baseball today (25 in each league), only eight were starting players for the same teams five years ago. Twenty of the 50 were starting for other teams then.

Most important, 22 of the 50 were basically unknown at the start of 1974. They were either in high school, the minor leagues or were part-time players in the majors just starting to make their mark.

Not since the early 1950s, it could be argued, has baseball received such a rush of youngsters who are perennial all-stars at the least, and perhaps Hall of Famers.

All these factors that have gone into baseball's burgeoning health operate below the surface. At the daily level, however every fan knows what the sum total of them means.

An atmosphere of general excitement and excellence has been reestablished. Consequently, the underlying assumption abides that something remarkable is going to happen. And it usually does.

Who would have anticipated that three of the last four World Series would be of the absolutely highest order. And that the other -- a four-game sweep in '76 -- would be a lasting testament to a Red team that belongs on a plateau with the 1927 Yankees.

Perhaps the ultimate result of this succession of fan feasts -- those 44-game Rose hitting streaks,.388 Carew averages and 25-3 Guidry pitching records -- was the Great Pennant Race of '78.

The best of AL races -- call it the Boston Massacre -- was perhaps only possible in baseball's current atmosphere of heightened expectations.

Could the Yankees have overcome a 14 1/2-game Boston lead, blown a 3 1/2-game lead of their own, won a playoff in Fenway Park, then rallied from two games behind in the Series if the entire sport had not been producing near-miracles with regularity for years?

Lovers of baseball should be advised to enjoy the fun while it lasts. No Golden Age lasts long.

Inflated salaries, reaching down to the lowliest $50,000 third-string catcher, have not run a franchise or three into bankruptcy yet.

However, the players' and owners' basic agreement must be renegotiated in 1980 and it will be a labor war worthy of the venomous '76 bettle when the owners fell on their swords.

Even Kuhn's contract runs out in 1982. If the owners long for a malleable man like Kuhn's predecessor -- Gen. William Eckert -- they can find one then.

Baseball's long decades of tranquility are gone forever. That century-old sense of continuity and tradition is precariously maintained at best.

Just as no fan could have delineated baseball's tumultuous rise in recent seasons, so it is equally impossible to guess the traumas of even the near future. In another five years, baseball will be transformed again, but on one can tell in what direction.