The day the New York Mets knew eventually would come has arrived: Darryl Strawberry took the first step toward leaving.

The step was taken Monday when Strawberry's agent, Eric Goldschmidt, made his client one of the first 21 players to file for free agency this year. The move was purely procedural. That Goldschmidt chose to act swiftly is not necessarily indicative of an increased desire on the part of Strawberry to sign with another club.Mets' Vice President Al Harazin called it "nothing that wasn't anticipated." Harazin Monday spoke by telephone with Goldschmidt for what he said was the first time since negotiations between Strawberry and the Mets were suspended in July.

At that time, Strawberry said he considered the Mets' only offer - he said it was three years for $9.1 million - to be insulting. Since then, three Mets' sources have said the club's offer had been substantially higher, as much as $16 million for four years, a figure Strawberry subsequently said would have prompted him to sign. However, neither Harazin nor owner Fred Wilpon has confirmed that the club proposed such a package.

Harazin said the Mets' plan is for Goldschmidt to make the next move, which could mean that the Mets will not discuss contract terms with Strawberry until after the free-agent filing period ends Nov. 4.

At that time, all clubs will be permitted to negotiate with Strawberry. Until then, only the Mets have that right to discuss financial terms.

Also among the 21 players who filed were New York Yankees' pitchers Tim Leary and Dave Righetti, disenchanted Los Angeles Dodgers' slugger Kirk Gibson and the Phoenix Cardinals' Vince Coleman, the perennial stolen-base leader in the National League. But Strawberry clearly is the most attractive player to have exercised pre-agency rights, and he will retain that identity, no matter who else among the remaining 73 eligible players file during the 15-day period.

Others filing included Yankees' pitcher Jeff Robinson, Philadelphia catcher Darren Daulton, Oakland catcher Ron Hassey, outfielders Franklin Stubbs of Houston and Rob Deer of Milwaukee, and St. Louis' Ken Dayley.

The Mets have contacted the agents of two potential free agents on their own roster - outfielder Pat Tabler and lefthanded reliever Dan Schatzeder.

The club already has exercised its option on the contract of reliever Alejandro Pena.Pena, who earned $875,000 last season, will earn $1 million next season.

The Mets also have initiated contract negotiations with Tommy Herr, the second baseman they obtained from the Phillies Aug. 31. Herr is among the 25 players on major-league rosters with at least six years of service and without contracts for next season who are not eligible for free agency because they have exercised free-agent rights in the preceding five years.

The incumbent clubs have until midnight Thursday to extend offers of arbitration or sign the players. Otherwise, the players become free agents.

The Yankees offered arbitration to pitcher Mike Witt Monday, thereby signing him for next season, with only his salary to be established. The Twins, Phillies, Brewers and Braves, respectively, offered arbitration to third basemen Gary Gaetti, shortstop Dickie Thon, second baseman Jim Gantner and pitcher Charlie Leibrandt.