BASEBALL PLAYS MUSICAL CHAIRS; A'S MCGWIRE LEADS TRADING FRENZY.

Byline: Matt McHale Daily News Staff Writer

The San Francisco Giants, whose eight-game lead over the Dodgers vanished in July, bolstered their pitching staff on Thursday's trade deadline by acquiring starters Wilson Alvarez and Danny Darwin and closer Roberto Hernandez from the Chicago White Sox.

The deal, which sent six minor-leaguers to Chicago for three potential free agents, triggered a flurry of activity that included Oakland slugger Mark McGwire to St. Louis and Seattle's red-hot rookie Jose Cruz Jr. to Toronto.

One player not traded was Texas' six-time All-Star catcher Ivan Rodriguez, who agreed to a five-year, $42 million extension Thursday afternoon after rejecting a deal worth $38.2 million last week.

In Seattle, the Mariners dealt furiously to shore up a shaky bullpen and to hold off the surging Angels. The Mariners obtained three relievers, including Boston closer Heathcliff Slocumb, deposed Toronto closer Mike Timlin and Blue Jays reliever Paul Spoljaric.

In the NL West, the focus was on the Giants, who led the third-place Dodgers by eight games on June 30. With Thursday's 4-1 victory over the Chicago Cubs at Wrigley Field, the Dodgers moved into a tie with San Francisco with two months remaining.

Alvarez (9-8, 3.03 ERA) is a strikeout pitcher and gives the Giants' rotation a second left-hander and four legitimate starters.

Hernandez gives the Giants two All-Star closers. A hard-throwing right-hander, Hernandez is expected to turn the ball over to Rod Beck for the ninth inning after taking it from Julian Tavarez for the eighth.

``This absolutely sends the message to our organization that we're committed to winning a championship this year,'' San Francisco general manager Brian Sabean said. ``You only get so many opportunities like we have this season, and we're determined to make the most of it.''

The White Sox, who engaged in a slugfest with the Angels in Anaheim on Thursday, made their moves despite trailing Cleveland by just three games in the AL Central. The best of the minor-leaguers they acquired are considered at least two years away from the majors.

But last season, they lost their top starter Alex Fernandez to free agency and were worried they would not re-sign Alvarez and Hernandez.

``We still believe we can win in 1997, but we were burned last year by the Alex Fernandez situation, and we couldn't allow it to happen again,'' said Sox GM Ron Schueler.

Cleveland also improved its pitching by acquiring veteran left-hander John Smiley from Cincinnati in a six-player deal and right-handed starter Jeff Juden from Montreal.

McGwire, who led the majors last season with 52 homers and is among the leaders with 34 this year, is second to Babe Ruth in lifetime home run frequency - one every 12.25 at-bats.

The Athletics received right-handed pitchers T.J. Mathews, Eric Ludwick and Blake Stein.

The trade reunites McGwire, 33, with St. Louis manager Tony La Russa, who was with Oakland from 1986-95, and former A's teammates Dennis Eckersley, Willie McGee, Rick Honeycutt and Todd Stottlemyre.

``I don't know how much longer I'm going to play major-league baseball,'' McGwire said. ``If I have a chance to help somebody go to the playoffs and World Series, I want to do that now. Oakland is rebuilding and I don't know how much longer it's going to take them.''

The A's feared they wouldn't be able to re-sign McGwire, whose 363 homers place him 42nd on the all-time list.

Third-place St. Louis is worried more about Houston's seven-game lead in the NL Central than re-signing McGwire.

Seattle, whose lead shrunk to a half-game heading into Thursday, was feeling more heat in the wake of the Angels' acquisition of Ken Hill earlier this week. The Mariners responded by obtaining three experienced relievers to save a bullpen that's blown 15 save opportunities and has a 6.40 ERA, worst in the majors.

The Mariners got quality help, but the price was steep.

The switch-hitting Cruz, who played last season for the Class-A JetHawks in Lancaster, had 12 homers and 34 RBI in his first 48 major-league games. Seattle gave up two more talented prospects - catcher Jason Varitek and pitcher Derek Lowe - to get Slocumb.

SWAP MEET

Thursday's 9 p.m. PST trading deadline did not pass quietly as many of the rumored players moved to contenders.Here are the winners of the deadline deals:

GIANTS: San Francisco obtained starters Wilson Alvarez and Danny Darwin as well as closer Roberto Hernandez from the White Sox for six minor leaguers.

CARDINALS: Mark McGwire and his 34 home runs left the A's for pitchers T.J. Mathews, Eric Ludwick and Blake Stein

MARINERS: Toronto played hard ball with pitching-poor Seattle forcing the Mariners to give up outfielder Jose Cruz, Jr. for relief pitchers Mike Timlin and Paul Spoljaric. Later, the Mariners traded two prospects to the Red Sox for closer Heathcliff Slocum.

INDIANS: Cleveland obtained starting pitcher John Smiley from the Reds in a six-player swap and added Jeff Juden in a trade with Montreal.

CAPTION(S):

3 Photos, Box

PHOTO (1--color) McGWIRE

(2--color) CRUZ, JR.

(3) Mike Timlin, who lost his closer job in Toronto, was among three relievers obtained by Seattle to shore up a faltering bullpen.

Associated Press

BOX: SWAP MEET (see text)