A YEAR AGO, a great deal had to go right for the Baltimore Orioles to win the American League pennant.

This year, a great deal has to go wrong for them to lose it.

The birds, who had the best winning percentage in the AL in both the 1960's (.566) and '70's (.590), once again enter the '80's as the soundest team in their league.

Few people have yet grasped the O's achievement in '79.

Over the past two seasons, the four powers in the East -- Baltimore, New York, Boston and Milwaukee -- have ranked 1-2-3-4 in total victories in all baseball.

West winner California was merely the AL's fifth-best team a year ago. And, although the Angels will probably win again, it's unlikely that they will deserve to be in the playoffs any more than they did last season.

In the excellent East, the best drivsion in history, the O's won 102 games, played .730 ball over a 100-game span when they buried all pursuers, and beat the Yank-Bosox-Brewer triumverate by a combined 33 games.

But except for Baltimore, the East appears to have passed its peak.

Boston is in decline. Don Zimmer should have been fired long ago. Carlton Fisk can't catch any more. Forget'em.

Only cash is keeping the Yankees afloat. Their starting pitching has soured this spring, and that was their trump.

Milwaukee, a rambunctious and overlooked Big Blue Crew, could still win 100, especially since a seak early-season schedule may cushion the blow of losing manager George Bamberger to heart surgery for the first couple of months.

But can the Brewers' atrocious bullpen and mundane starters outlast one of the best pitching staffs in history -- the one that lurks in Baltimore?

This division looked ripe for a young dark horse to make up ground -- a team like Sparky Anderson's Detroits. But Anderson's traditionally bad touch with pitchers has struck again this spring and the Tigers now look a long shot.

This fine division needed bad luck to undermine the O's so that a proper sense of drama could be maintained.

And, right on schedule, that ill fortune has arrived.

Ken Singleton may need minor knee surgery. Dennis Martinez will begin the season on the 21-day disabled list (arm muscle tear). Lee May looks terminally decrepit. Eddie Murray has a goot (instep) problem. Gary Roenicke needs new contacts for a blind spot in one eye. Doug DeCinces and Mark Belanger spend more time as labor negotiators than ballplayes.

The Birds, after losing their last eight exhibition games, might actually have enjoyed a two-or-three week labor strike to start the season. Singleton, Martinez and company would have had more time to heal.

Now, matters will apparently start on schedule, and the Orioles, who have mastered the atrocious April start three years in a row, must play the Yanks six tims in the first 20 days.

Nevertheless, the Birds are the strongest pick in any of the divisions. They are the only team in baseball close to jelling into the sort of confident champion that could win back-to-back world titles, as Oakland, Cincinnati and New York all did in the '70s.

It's not farfetched to assume that Mike Flanagan and Martinez, as a tandem, can equal their 38-25 mark of '79. One was above his par; the other below his.

Palmer, who's been healthy in Florida, and Scott McGregor, who looked like Whitey Ford in three postseason starts, could easily surpass their 23 wins in '79 when they missed 25 starts. These could be four starters for the time capsule, though Martinez' conehead tendencies persist.

Steve Stone, after assimilating Bird pitching theories, and learning a forkball, had a 2.94 ERA in his last 13 starts.

Many insiders suspect the O's are accidently rid of free agent Don Stanhouse just in time. His exodus may hurt clubhouse morale more than it hurts the team ERA. If Tim Stoddard, Sammy Stewart and Dave Ford don't more than fill his space, then it will contradict a quarter-century tradition of the Birds producing the best young arms in baseball.

The Brewers, who won a quiet 95 last year, are a pleasingly constructed offensive machine with staggering stats and the potential for even more wreckage.

Sixto Lezcano (.321, 131 RBI), Gorman Thomas (45 homers, 123 RBI), Ben Oglivie (29 homers), Paul Molitor (.322), Cecil Cooper (.308, 106 RBI), Charlie Moore (.300) form an amazing nucleus to blend with slick shortstop Robin Yount and aging third basemen Sal Bando and Don Money.

Oh, yes -- Larry HISLE, WHO HAD 119 AND 5 RBI in back-to-back years before being injured and dropping to 14 last year, is coming back. Bambi's Bombers indeed.

That nickname also applies, unfortunately to the entire pitching staff, which gave up 162 homers. Only one thing saved 'em: Bamberger issued death threats to any pitcher who walked anybody. The Brewers allowed only 381 free passes -- 69 less than any other team in baseball, and 279 less than Oakland.

After five Brewer starters (their names and photos can be found on post-office bulletin boards in Milwaukee) allowed more hits than they had innings pitched. Not one Oriole had that indignity.

And Milwaukee has no bullpen. Bruce Stter had 13 more saves than he entire Brewer arson squad. Brewer pitchers led the majors in complete games because starters would only surrender the ball to relievers at gun point.

Those who are nauseated by the Yankees' tactic of trying to buy the pennant should have a pleasant summer. The New Yorkers, a dead-in-the-water fourth last year, will have to play their pinstripes off just to finish third.

The Yanks have two fine starters -- Ron Guidry and Tommy John, one excellent reliever -- Goose Gossage, and one slugger -- Reggie Jackson. Behind that, we find a wealth of mediocrity and age.

John, Rudy May (already injured), Luis Tiant (finally obese and over-the-hill), Graig Nettles (slowing down) and Lou Piniella were all born before the end of World War II.

New acquisitions Bob Watson, Rick Cerone and Eric Soderholm -- all righty hitters -- will be introduced to Yankee Stadium's Death Valley. Bad stats, ahoy. New center fielder Ruppert Jones hit 21 homers last year -- but 18 of them were in the miniscule Kingdom. He may not hit 10 this year.

The Yankee search for third, fourth and fifth starters has reached the serious stage. Tom Underwood, 15-30 with Toronto, has proven that he can be a .500 pitcher with contender (33-2.) -- but that's his limit. Ed Figueroa is close to joining Don Gullett as an irreparable physical wreck.

The Yankees, 10th in scoring in '79, are old and slow. They've dropped from 164 steals in '77 to 64 last year. New York will do well to match its 89 wins of '79.

The Red Sox are victims of the Danny Ozark syndrome. They won't replace Zimmer because he's so decent, so popular, and so obviously a competent lifelong baseball man. "Look how any Zim's won," its said. But look how many he should have won.

Last year, Boston outscored its opponents by 130 runs, second only to the Birds' superiority of 175 runs. Yet the Bosox finished four wins behind the Brewers, who only had a 85-run advantage. Could that measure Bamberger's edge over Zimmer?Houston came within 1 1/2 games of a flag in '79 while outscoring its opponents for the year by one run.

The Red Sox, reduced to givein a AA rookie southpaw (Bruce Hurst) a starting spot in the rotation, and trading for Dave Rader (.203 in 305 at bats) to replace Fisk at catcher, have major problems ahead.

Zimmer is so stubborn that he insists on starting old free agent Tony Perez at first, instead of shifting the dead-armed Fisk there, where he might have his greatest hitting year. "I can't get to first base with Don Zimmer," jokes Fisk morbidly, consigned perhaps to both the bench and the doghouse at 32 if his arm isn't miraculously cured.

The Tigers, after a bunch of sharp moves, need only starting pitching, which, unfortunately, is still the heart of the game.

Richie Hebner replaces deadweight Aurelio Rodgiguez at third. Anything would be an improvement. For years Rodriguez has gotten away with playing like one of the corpses that gravediggers Hebner buries in his offseasons.

Handing center field to rookie Kirk Gibson was a no-lose deal, since trading troublesome Ron LeFlore for lefty Dan Schatzeder was a smart swap, even without taking into consideration the fact that LeFlore would have become a free agent after '80. Schatzeder is one of the game's best hidden prospects.

Anderson, however, needed some luck on the mound and he hasn't gotten it. Mark Fidrych is back in the minors, and Dave Rozema has enrged Sparky's fundamentalist soul by missing a team flight due to the greater urgency of judging a wet T-shirt contest.

The West, once again, should be a close contest between baseball's two highest scoring teams: the Angels (866 runs) and Royals (851). The pair even swapped sluggers -- Al Cowens to California and Willie Mays Aikens to Kansas City.

That, however, doesn't begin to touch the problems. Neither team can pitch a lick -- ranking 21st and 22nd in ERA last year. Neither has any semblance of a bullpen, now that K.C. has lost Al Hrabosky. And neither has a competent major league shortstop.

Compounding miseries, the Angels lost Nolan Ryan to free agency, while K.C. lost catcher Darrell Porter to an alcoholism rehabilitation program.

K.C. should miss Porter more. He was a bonafide unknown star (over 1,000 RBI, runs and walks), while Ryan (16-14) remains baseball's millionaire mediocrity.

The Royals may also miss manager Whitey Horzog, unless quiet rookie skipper Jim Frey, an excellent hitting coach, can transform the slumbering bat of super-flop Clint Hurdle, who has gone from the cover of Sports Illustrated to .236 at Omaha.

The West's amusing mystery team is Texas, which has no chance whatsovever, except in preseason polls.

Starting with the most overpaid and overpublicized outfield in baseball. Al Oliver has averaged under 15 homers and 80 RBI for the last 11 full seasons, yet continues to tout himself as the game's best "pure" hitter. Pure baloney. Mickey Rivers once stole 70 bases; last year old man Rivers was down to 10, ranking his 83rd in thefts in baseball. Ritchie Zisk, since coming into a 10-year contract worth millions, has gone from a 30-homer, 100-RBI plateau to 20-and-70 level the past two years.

The Rangers have a great bullpen, yet are so fundamentally unsound and scatterbrained that they were 23-30 in one-run games last year. Their front office is so bazzaire that they have just traded for another first baseman -- Rusty Staub to go with Pat Putnam, etc.

Out of this mutinous assemblage, look for unheralded frisbee-tosser Steve Comer (pronounced like "coma" in Tuscaloosa) to win 20. The rest of the American League -- East and West -- looks like six versions of the old Washington Senators.

Cleveland and Minnesota, both barely over 500 last year, should slip below this time, though neither is truly dismal.

Cleveland scored more runs than the Orioles last year, while Minnesota has Gene Mauch, the manager who proves there will always be a market for a man who can make a bad team poor. With a trio of incognito .300 hitters (Rob Wilfong, Glenn Adams, and Ken Landreaux) Mauch has a good chance to finish fourth-or-lower for the 19th time in his 21 seasons.

The remaining four clubs -- Chicago, Oakland, Seattle and Toronto -- are so bad that they offer the same camp pleasures as an Andy Warhol epic. A manager Billy Martin will now contend with such gentlement as Matt Keough (2-17) and Rob Picciolo, who drew three walks in 348 at bats.

For those who wonder what AAA ball looked like before expansion, these clubs are it. Only the White Sox show any signs of hope for the future with a quarter of young southpaw starters, led by curveballing Steve (Rainbow) Trout.

However, the combination of third-base vacuum (not cleaner) Kevin Bell, who had an hallucinatory .923 fielding percentage, plus a schedule that opens with 23 straight games against the East's Big Four, should ensure a short Chicago season.