"Baseball works in mysterious ways," Jack Critchfield of Florida Progress, a member of an investment group seeking a franchise, said at a news conference today in St. Petersburg. "I never felt good we were going to get the Mariners for various reasons, but I feel awfully confident about this one." Some Hurdles Ahead

There are reasons, however, why the Giants might not reach St. Petersburg. At the owners' meeting in June, Mr. Vincent gave Mr. Lurie approval to explore all options, including moving or selling the team to someone who would move it, but that action was not tantamount to approval.

The Los Angeles Dodgers' owner, Peter O'Malley, whose father induced Horace Stoneham to abandon the Polo Grounds and move to California with the Dodgers, was said by other owners and officials to be concerned about the prospect of losing the Dodgers' historic rivalry with the Giants. If Mr. O'Malley wants to oppose the move, he would need to recruit only three other owners to block it.

And in the American League, some owners do not like the idea of ceding Florida to the National League. What About the Marlins?

Then there are the Florida Marlins, who paid $95 million to join the National League.

Carl Barger, the Marlins' president, was quoted last winter as being opposed to the move of an established team to the Tampa Bay area, but he and Wayne Huizenga, the Marlins' owner, held a news conference last February to alleviate fears that they would block such a move.

In statements yesterday, they reiterated their support for a team in the Tampa Bay area.

There is also the issue of realignment. Last month, acting at the request of six National League owners, Vincent ordered the Cubs and the St. Louis Cardinals to move to the Western Division and the Atlanta Braves and the Cincinnati Reds to move to the Eastern Division.

One of Mr. Vincent's reasons was the geographical rivalry that could develop between the Braves and the Marlins, who are being placed in the Eastern Division. If the Giants move, the area could become a baseball hotbed, and it wouldn't make sense to have the three teams in different divisions.