In mythology, the Hydra was a nine-headed monster that grew two new heads in place of each old one that Hercules chopped off.

Those who play against the Baltimore Orioles must sometimes begin to think of them as the Chesapeake Hydra.

Of the nine positions in the Bird lineup this year, seven are inhabited by creatures with two heads.

That is the central and little-understood mystery of this O's team that, counting playoffs, has a 105-58 record.

In the World Series, the Orioles are fielding what appears on the surface to be on of the homeliest lineups in postseason baseball history.

The Baltimore nine Wednesday includes men who are hitting .167, .230, .239, .249 and .254. These worthies had no hidden powers, either, averaging only eight homers per man.This does not count the O's pitcher, hitting .000.

What must be grasped about the Birds is that they do not have nine starting players but 15, anyone of whom can appear in the starting lineup without an eyebrow raising.

Only two Orioles -- Ken Singleton and Eddie Murray -- play in all 159 Baltimore games this season. At the seven other spots, Manager Earl Weaver platooned multiple players either full time or part time due either to strategy or injuries.

For example, the O's "left fielder" is not famous. But he hit 36 homers with 98 RBI and 91 walks this year.

Neither is the Oriole "second baseman" well-known. But, with a slight statistical exaggeration, he had 94 RBI and 160 runs produced in '79.

As for the Birds' "designated hitter," he had 28 homers and 94 RBI.

Why are these players with All-Star statistics so anonymous? Obviously, because they are not one player, but two.

After Singleton, with his 35 homers, 111 RBI and 109 walks, the Orioles' most valuable player was probably their combined left fielder -- Gary Roenicke-John Lowenstein. The pair, in addition to the stats already mentioned, scored 93 runs, stole 17 bases and had 24 doubles.

Between them, Roenicke and Lowenstein had fewer plate appearances than either Singleton or Murray.

In the same category are Lee May and Pat Kelly -- the 70-year-old designated hitter -- who, in fewer trips to the plate than Singleton or Murray, had those 28 homers, 94 RBI, plus 84 runs and a .260 average.

for illustration, Pittsburgh's $800,000 superstar, Dave Parker, played almost every Pirate game this season and had 25 homers and 95 RBI.

The Orioles, by contrast, got that much power production, or more, from four different spots in the lineup -- first base, right field, left field and designated hitter.

In fact, the Orioles' almost invisible second basemen -- Rich Dauer and Billy Smith -- combined for 94 RBI, 15 homers, 81 runs and 18 game-winning-hits.

It must be noted that Dauer-Smith had 668 at-bats, perhaps 100 of them when Dauer was subbing at third for Doug DeCines. But, if that is the case, then perhaps some of Dauer's contributions should be added to DeCinces' decent power totals of 16 homers and 61 RBI in 422 at-bats.

However you cut it, the Orioles look better and better, and their runaway victory in the AL East is less a paradox.

Other O's are also somewhat better than they seem. For instance, Bennie Ayala's stats should be added to those of Al Bumbry because, when Ayala played, it usually meant that Roenicke went to center and Bumbry rested against a southpaw.

The bats of Bumbry-Ayala had 95 runs scored, 13 homers, 62 RBI, a .280 average and 37 steals while hitting either first or second in the order.

Even the supposedly weakest offensive links on the Oriole chain -- short- stop and catcher -- don't look so miserable when we look at combined totals.

Shortstops Kiko Garcia and Mark Belanger, in 615 at-bats, had 82 runs scored and 61 walks, despite their .221 average.

Perhaps a bigger surprise is the Oriole catchers. The gimmick there is that pinch hitter Terry Crowley's stats should be added to those of Rick Dempsey and Dave Skaggs because Crowley usually hit for one of them in the late innings, while the other would then come in to catch.

Of course, Crowley also pinch-hit some for the shortstops, but let's not nit-pick. We're trying to make a board point here, not create some kind of exact science.

The catchers, plus Crowley, hit .250 over 568 at-bats with a creditale 65 runs, 63 RBI and 65 walks. Not bad at all, considering that Dempsey-Skaggs may have done the best total defensive job of catching in the American League.

For those fascinated by minutiae, it is true that Garcia played a tad at second base, and Kelly saw action in left field when Lowenstein had a sprained ankle and had to DH. once more, the statistics of the Hydra are not precise. Weaver, the creator of the monster, likes to wheel and deal too much for that.

Nevertheless, the total picture becomes clearer. We can understand how the Orioles actually out-homered Pittsburgh in '79 by a significant 181-149 margin, and how the Pirate edge in runs scored was only 775-757.

This is not to say that the Bucs' hitting isn't better than Baltimore's. It is. Especially when you factor in the 28-homer, 94-RBI contributions of May-Kelly who can only pinch-hit, not DH, in the series. The total power stats from the No. 9 spot in the Baltimore order, were it held down by pitchers and frequent pinch hitters, would probably only be half that of May-Kelly.

However, the offensive difference between the Lumber Company and the Hydra is not as great as a glance at the opening lineups might indicate. The Pirates, figuring in the DH vairable, have an attack about the equal of the Milwaukee Brewers and some place slightly below the majors' three best scoring teams -- California, Kansas City and Boston.

The Orioles' sneaky attack is on the next level below those star-littered lineups.

That, however, is a vastly higher ranking than the Orioles' glamorless batting order would receive if we were not aware of its two-faced, duplicitous and downright two-headed nature.