First baseman Jack Clark's move from the St. Louis Cardinals to the New York Yankees was the biggest, but not the only, indication that free agency has returned to major league baseball.

Twelve years after the great experiment began and two years after it appeared to have died, the open market has been in operation this winter. For sure, there are differences. No player has received more than a three-year contract, and no player has come close to receiving the $6.8 million Fred Lynn got from the Baltimore Orioles in 1984.

But compared to 1985 when Detroit's Kirk Gibson didn't get one offer, and 1986 when National League batting champ Tim Raines couldn't find work, this winter has been a bonanza.

Clark moved from the Cardinals to the Yankees; center fielder Brett Butler moved from the Cleveland Indians to the San Francisco Giants; center fielder Chili Davis moved from the Giants to the California Angels; and outfielder Mike Davis moved from the Oakland Athletics to the Los Angeles Dodgers.

What's more, there has been a lot of talking, and that has led to teams being more decisive and looser with their checkbooks than they were a year ago. With St. Louis and Los Angeles both interested in Gary Gaetti, the Minnesota Twins rushed to re-sign their third baseman yesterday. He accepted a three-year contract that could be worth as much as $4.2 million.

Also yesterday, the Kansas City Royals re-signed pitcher Charlie Leibrandt. He received a two-year contract believed to be worth $2.4 million after the Yankees had expressed interest.

This week's activity pretty much drained the free agent market as today's deadline approached. Players who haven't signed by midnight can't re-sign with their previous teams until May 1. But 24 hours before the deadline, there wasn't much left.

Of 33 players still on the market, Houston reliever Dave Smith is considered the best. Other attractive free agents include pitcher Atlee Hammaker of the San Francisco Giants and pitcher Bill Gullickson of the Yankees. However, most of the remaining free agents are aging veterans or players who won't be offered contracts by their current teams. Among those are Tom Paciorek of Texas, Gary Matthews of Seattle and Steve Garvey of San Diego.

"I don't know if we're ever going to see out-and-out bidding wars again, but the market does appear to have corrected itself somewhat," said agent Tom Reich, who negotiated the deal for Clark.

Baltimore-based agent Ron Shapiro agreed. "I think free agency is back," he said. "For quality players, it's clearly back. I don't think I'm surprised. I think the decision of the arbitrator {that owners had illegally conspired to end free agency} had an impact. But I emphasize I'm talking about top quality players. I don't see a flooded market for average players or those who've had subpar years. And the contracts remain shorter."

The remaining suspense this winter will center around Smith, Hammaker and Gullickson.

Smith, 32 and with a history of elbow problems, wants a three-year contract with a base annual salary of $1 million. The Houston Astros have refused to go higher than $850,000 and two years, and while Smith doesn't appear to have another solid offer, he was seen in the office of Oakland General Manager Sandy Alderson this week.

The Giants increased their offer to Hammaker this week. It's believed to be a two-year deal worth about $1.2 million, which is close to what the Texas Rangers have offered. The Cleveland Indians are also in the ballpark.

The Giants apparently didn't expect to have so much trouble re-signing a pitcher who missed the entire 1986 season after rotator-cuff surgery and won only 10 games in 1987. He also pitched poorly in the National League playoffs, especially in Game 7 when he lasted two innings and dug the Giants a 4-0 hole.