When Lee May was traded from Houston to Baltimore in 1975, his old National League buddies called to needle him.

"Gee, Mo, sorry to hear you got sent down to the American League," they teased. "Good luck - in the bushes."

"Coming to the American League was a downer then," recalls Ken Singleton, traded to Baltimore from Montreal the same season. "It was almost like going to AAA. We National Leaguers hardly thought the other league existed."

In those days, the NL had more stars, better teams, a faster and more aggressive style of play. No one could gainsay it. The gap was painfully obvious.

Now, baseball has reached the healthy stage where it is probably impossible, and unfair, to decide which league is better. The AL is in its second year of relative parity.

It is not impossible, however, to say which league now seems more interesting - it's the American. That's a new development, and a shocker.

Arguments over individual players cause debates. Disagreements over team loyalties, however, cause fist fights. Affections simply run deeper over teams - something to do with tribal instincts and territorial imperatives, no doubt.

That's the American League's bonanza.While the NL still has great players, it now seems to lack vivid teams. The AL has more facinating clubs - at least seven genuine contenders - than the National can keep up with.

The balance of talent between the two loops is roughly equal - thanks to years of interleague trading, free-agents auctions, and an influx of young AL stars.

The NL probably has a more ferocious coterie of everyday stars - agents like George Foster, Dave Parker and Dave Winfield who epitomize muscle-in-its-prime - while the AL has perhaps a more glamorous selection of moundsmen like Ron Guidry, Jim Palmer and Tommy John.

Let's not start making endless lists. Or screaming. Jim Rice and J. R. Richard certainly contradict the trend.

What is of interest, what captures our attention every day, is the life history of teams. And that, in the last two years, is what draws our eye increasingly to the AL.

"Just four years ago, it seemed like the AL only had three teams worth talking about - Oakland, Baltimore and maybe Boston," Singleton commented. "They won every year and you hardly noticed the other teams.

"Now, it seems like every series in every town is a war. You've got at least nine teams that honestly think they can get to the World Series and they play like it - the way we used to in the National League."

Last year the American League East alone had four 90-win teams - more than the entire NL (three). The AL East was, by acclamation, the best division in baseball.

Now, gaze at what has happened.

The mighty AL East gained overall strength as New York, Baltimore and Milwaukee all made offseason personnel improvements. Yet the AL West suddenly looks almost as good.

Head-to-head, the East had only a three-victory advantage over the West after a third of the season.

Four AL West teams were within two games of first place - all with winning percentages of .550 or better. Nothing excites a fan more than a growing, still blossoming team. Both California and Texas, free-agent free-spenders, have that look.

Last year in the AL East, it was Milwaukee that saw its million-dollar expenditures create a powerhouse that led the majors in homers and scoring. This season, it is Baltimore, with its rich farm system producing a surplus of pitchers, that has created a team dreaming of 100 wins.

Those who study the American League box scores see the intensity of an August pennant push being forced back into May and June. Every injury, every star going to even the 15-day disabled list, seems to reshuffle the teams in each division.

No sooner do the Orioles rip off a 26-6 blitz than their bats go sour, their arms get sore and the pack bunches once more. Just as the Angels reach the lead, Rod Carew is sidelined for a month. Time for new deal.

The National League lacks this dynamism.

Just as the AL of 1974 was a three-team league, so the NL of the present has that danger. Los Angeles, Cincinnati and Philadelphia have bossed the circuit for several years. Their pursuers seem a mite resigned.

Even when opportunities present themselves, teams like San Francisco, Houston and Montreal - strong teams - seem unable to make a dramatic move. Their lingering weaknesses remain palpably obvious. The bits of patchwork and old string show.

The National League is ripe for a new champion. Yet no team seems anxious to take the bit - with the possible exception of the Dick Williams-led Expos.

The champion Dodgers, are in serious trouble. Losing three free agents last winter, the Dodgers, after two amazingly healthy years, have finally hit their injury come-uppance. Doug Rau, lost for the season, and Andy Messersmith, ineffective and disabled-list bound, ought to kill the Dodgers' division hopes. The ghost of Tommy John should haunt the dodgers' tight-fisted brass.

But who will supplantthe Dodgers? The Giants cant't hit a lick and grumble about the nasty Bay Area press second-guessing Manager Joe Altobelli. They should be sentenced to a fortnight of listening to the Philadelphia harpies of the fourth estate.

The Houston Astros, after years of playing far below their abilities and infuriating anyone who tried to root for them, finally played over their heads for a third of the season. And had a whopping one-game lead to show for it. One good slump should unhinge them.

While the Dodgers are aged and injured, the semidismantled Reds might have leaped into the void. But, without Pete Rose and Sparky Anderson, with Joe Morgan and Johnny Bench playing on tape and borrowed time, they are happy to stay a few games over .500. Where, oh where, is Tom Seaver (2-5)?

The league's mystery team - what else is new? - is the Phillies, the only NL bunch capable of coalescing into a club as good as the recent repeat champions from Oakland, Cincinnati and New York.

The Phils thought they could hide their nonexistent bench, and their barely existent manager, behind expensive front-line talent. Sputter, sputter. All the Phils need is one good sore arm to be really in deep waeter.

The Expos, with an excellent starting lineup, have been the NL's bright spot - a young, rising, still unformed team like the Angels, Rangers, Orioles, Brewers and even Tigers in the AL.

"It wasn't so much that we lost that bothered me," said Phillie Pete Rose after Montreal had swept a series from Philadelphia last week, "it was the way (veteran) Tony Perez had the Expos acting like they were supposed to win."

Yet look at two of the tires on which the Montreal pitching rotation travels - Bill Lee and Ross Grimsley. What a pair of potential mush-balling flats.

The idea here, of course, is not to denigrate the NL, but merely to give a needed dose of humility.

"We're still the better league," insisits Rose, voicing the general NL opinion. "You gotta be a better athlete to play on all the synthetic fields we got.

"Hey, look at what we do to 'em in the All-Star Game."

"They win the All-Star Games," points out Baltimore Manager Earl Weaver, "but we've won five of the last seven World Series."

All right, boys. Stop kicking and biting.

The salient point is that a once sick league is now well. In fact, thanks to the designated hitter, the AL now produces more offense in all categories than the NL.

Each league has its identity - a secure and valid one.

The NL accents modern parks, synthetic symmetrical fields and speed. The AL is rich in esthetic grassy havens of the home run where a man can still lay down a bunt that won't roll to the warning track.

The NL emphasizes the traditional strategies - pinch hitting, gangs of relief pitchers. By contrast, in the AL, the DH produces a plethora of durable 20-game winners who are never lifted for a pinch swinger, while also providing a home for the aging bats of chaps like Willie Horton, Rico Carty, Lee May and Rusty Staub.

Each has its chams. What makes the American League so vital, however, is the nature of its many contending teams - most of them either at their peak or else young, aggressive and still defining themselves.

In other words, it sounds a lot like the National League of just a few years ago. CAPTION: Picture, Dick Williams