PITTSBURGH -- The Pittsburgh Pirates embraced "Turtle Power" early.

By their first West Coast trip in mid-April the Pirates were already firm believers in the mythical force spun out of the hit movie, "Teenage Mutant Ninja Turtles."

And when the Pirates returned from the trip with a 10-3 record, the fad naturally continued. Turtle posters now dominate the clubhouse and "dude-speak" permeates team banter.

As fleeting symbols go, this one works fine. Much like the movie, the Pirates were a big hit in April, taking over the lead in the National League East on April 22 and, except for one day, maintaining that position. They hold a four-game lead over Philadelphia and Montreal.

Crazes tend to dissipate, but this one appears fully capable of lasting well into August -- to say nothing of September and October. Pittsburgh proved as much last month when they struggled through a near-disastrous road trip (2-6) only to return home and promptly win five of six against the San Francisco Giants and Los Angeles Dodgers. The centerpiece of the streak was a 6-5 Memorial Day victory over the Dodgers, won with a five-run rally in the bottom of the ninth.

"This is the type of game that can make you think you can do it," said Andy Van Slyke, the center fielder who has rebounded from a sub-par, injury-riddled 1989 season to hit .331 the first two months of 1990. Moreover, he continues to play the best center field this side of Kirby Puckett.

"What I like about my team is it has talent," said Manager Jim Leyland, who, as always, remained calm through the road slump. "You feel like if you prepare for every game, you've got a good shot at winning. This is a pretty talented ball club."

The Pirates' talent was apparent mostly only to Leyland in the spring. Last year the Pirates finished 74-88, 19 games behind the first-place Chicago Cubs.

But Leyland believed much of that was due to major injuries to Van Slyke, Mike LaValliere, Sid Bream and ace reliever Jim Gott, all of which happened in the first month of the season.

This year, the Pirates have been healthier and their talent is evident. Start with Barry Bonds (.306, 12 homers, 39 RBI), Bobby Bonilla (.294, 12, 41) and Van Slyke (.331, 6, 27), probably the best outfield, offensively and defensively, in the league.

In the infield, shortstop Jay Bell and second baseman Jose Lind have been productive hitters and dependable, at times spectacular, fielders. Lind slumped badly in 1989, but this year is hitting .335 and has reaffirmed his status as one of baseball's top fielders.

The Pirates made few headlines in the offseason, but the quiet moves they did make have paid dividends. Don Slaught, acquired from the New York Yankees, has teamed with LaValliere to give the Pirates a potent left-right catching combination.

Wally Backman, acquired from Minnesota after a .231 season, has platooned at third base and hit .328. Moreover, his scrappy play has proven inspirational. Equally important, he is an ideal leadoff hitter, which has enabled Leyland to move Bonds down to the fifth spot in the batting order, where he shows promise. Bonds, who has never had 60 RBI in a season, is on a pace to knock in 80 or more runs.

"We used to hate Wally Backman," said Bonds. "When he was with the Mets, he used to beat us all the time. You look up and he's always on base. We've got a great nucleus of a club and it helps when you have guys hitting .300, who are not expected to hit .300."

Equally unexpected has been the Pirates' pitching staff, paced by starters Doug Drabek (7-2, 2.78 ERA) and Neal Heaton (8-1, 2.84 ERA). Heaton, a sub-.500 pitcher throughout his eight-year major league career, this spring developed what he calls a "screw-knuckle-change" and it has given him an out pitch to complement his usually reliable fastball.

The Pirates' bullpen has shown exceptional depth. Bill Landrum, who produced 26 saves after getting a chance to pitch when Gott was injured in 1989, shares closing duties with free agent Ted Power. Converted minor league outfielder Scott Ruskin is a middle man with an exceptional curveball. Bob Patterson (4-1, one save) has been a spot starter and middle reliever.

"This is the deepest club I've ever had," said Leyland. "It gives me more versatility. Everybody on this team feels a part of it."

The Pirates' biggest weakness was thought to be hitting against left-handed pitching. Van Slyke and Bonds are both lefties; Bonilla and Backman are switch-hitters who hit best from the left side. The Pirates' 10-7 record against left-handed starters this year has not stopped rumors of a possible deal for a right-handed, power-hitting outfielder. If that happened, Bonilla likely would move from right field to first base.

But the Pirates appear in no rush to make such a move, their security aided by the Mets' struggling below .500.

"In 1986 and '87, every win we had was exciting," said Bonds. "This year, we don't get as excited. We know this is a team capable of being a contender all season."