Here it is, verging on St. Swithin's Day, and the two major league pennant races are so disordered, so naked of logic as to make even that honored churchman an unbeliever. For weeks, baseball fans have been asking in their quaint American way: What the hell is going on here? Dodgers are dead already -- dead last with barely half the season marked off.

Their companions of the last World Series, the champion Yankees, have their own troubles, and bad ones. They are in fourth place, and at least half dead -- if the plug has not already been pulled on them.

Now then, if the Dodgers are not of it, then the decent belief would be that the Reds and Phillies should be up there on top of the two NL divisions.Blather and nonsense. Basic logic has no place here. This is not your ordinary baseball season.

It's the year of the impostor. A team calling itself the Montreal Expos is confortably atop the NL East, with the Phillies struggling in the middle of the pack. Didn't there used to be an NL expansion team named Montreal with a habit of finishing last, and didn't it start the season as a 40-to- shot, according to Jimmy the Greek, who now says it as a 7-to-10 favorite?

It's even more flabbergasting in the NL West. Remember the Houston Astros, the team that finished a horrible last in 1978, 21 games out of it in their division. They're the hottest club in the league, with the majors' biggest lead, over the second-place and highly surprised Cincinnati Reds.

Guess who's leading the AL East now that the Yankees are so messed up they're 10 games out of it and in fourth place? Li'l ol' low-budget Baltimore, that's who, with a bulge over Boston. Same Oriole team that was sunk in fourth place last year, nine games behind New York.

That brings us to AL West and the question of what happened to Kansas City the defending champs? Two things happened to the Royals -- Texas and California, who are jockeying for the lead -- and the explanation is simple. The Rangers and Angels are simply a year behind schedule. They were supposed to be up there last year, not this year. one. Their pitching staff, Burt Hooton expected, is a wreck, with a ghastly 4.17 earned-run average. They have also become the NL version of the Red Sox, with their miserable road record, winning only 10 of their first 33 road games.

Tom Lasorda is learning that his baseball deity, the Great Dodger in the Sky, favors his team only in proportion to the kind of pitching he gets. From the Great Dodger in the Sky, Lasorda has been getting mostly Skylab.

It is precisely because the Astros are pitch-rich that they are on top and winging. Good old Joe Niekro is the bellwether of a youngish staff that leads the league with its 3.17 earned run average. The Astorus have risen above their reputation as the NL's third-worst batting team to run away from the Reds and their so-so pitching.

Montreal's starting rise in the NL East also is premised on its pitching (second to Houston's). No Montreal regular is hitting 300 but there's power down the line, and tough-talking Manager Dick Williams in a plus. He has been there before as pennant winner for the Red Sox and A's and can strip a team of any inferiority added to it.

The Phillies are, so far, the undeniable phlops in the NL East. This was the year, with Pete Rose and everything, that they were supposed to breeze by the Pirates, the only other club of seeming merit. Rose is without blame, with his high-average hitting and slick first basing, but otherwise the team hasn't had the wood.

The Phils' failure to hit all those home runs they were supposed to hit is one of the reasons for the reports every other week that Manager Danny Ozark will be dunked. The chief offender is Greg (Muscle) Luzinski, who hit 74 homers in the last two seasons but is not yet in double figures this year. That's bad for the Phillies. Also, Ozark's managing is not believed to be very inspiring.

The Yankees simply came apart the day Rich Gossage broke his pitching thumb in a senseless clubhouse scuffle with a teammate. The six weeks he was supposed to be out stretched to 10 and more, and the Yankees lost the most intimidating weapon in the league. They were cut down to size. On top of that, add injuries to Reggie Jackson and Ed Figueroa and the meddling of owner George Steinbrenner, and Manager Bob Lemon was in trouble.

Streinbrenner's prescription was to bring back fiery Billy Martin, the man he fired last summer. Martin's mission was to stimulate the fading Yankees with his special kind of excitement, an odd command inasmuch as it was after an overdose of Martin that Lemon was brought in last summer to help the squabbling Yankees cool it.

Martin has tried to make peace with his old antagonist, the suspicious Jackson, who is back in the lineup but still in a sulk. In a peacemaking gesture, Martin said, "We can't win without Reggie," and Jackson would agree to that, but his relationship with his manager is still arm's-length. Also, it may be noted, many of the Yankees are getting old.

In the Al West, defending champ Kansas City isn't on top because its decent pitching of last year has decayed into the worst in the league. Its defense is next to worst and only its hitting has kept it in semicontention with the Angels, Rangers and surprising Twins.

Minnesota is an example of the wonderful illogic sometimes summed up as, "That's baseball." Without seven-time batting champion Rod Carew, the Twins are doing better this year than they did with him last year. They found an astonishing new hitter in major-league leader Roy Smalley, who never before has hit more than .273, and that's baseball.

Texas is up there because it found a pitcher named Jim Kern, who is next to invincible as a relief man [10-1] amd has the league's best ERA at 1.66, a most-helpful statistic.

The Angels are doing it with the big performances from their expensive free agents, Don Baylor and Bobby Grich, who was supposed to deliver in 1978 and didn't.

Baylor is thumping away with 19 homers, 75 runs batted in, and has raised his batting average from .255 to near .300. Grich [.251 last season] is over .300, and when Carew, a casually for more than a month, picks up his splendid bat again, the rest can beward.