Six men pleaded innocent yesterday in a Pittsburgh courthouse to all drug charges filed by a federal grand jury that is investigating alleged cocaine sales to major league players.

The attorney for a seventh defendant said "without question" a major league player implicated his client. Statements made by the attorney, Adam O. Renfroe Jr., seemed to enhance the possibility that players will be called to testify if any of the defendants go to trial.

Renfroe represents Curtis Strong of Philadelphia, who is expected to be arraigned shortly on 12 drug charges. Yesterday, Renfroe said, "I am anxiously awaiting the time I can cross-examine that ballplayer. Whoever he is, (he) is a sincere . . . abuser of that drug.

"When I have to present a ballplayer's name or cross-examine a ballplayer, I'm sure millions of people around the country will be anxiously waiting to see who it is."

J. Alan Johnson, U.S. Attorney for the Western District of Pennsylvania, declined to comment on Renfroe's statements. Johnson directed the 14-month grand jury probe that produced the indictments. Earlier this year, more than a dozen major league players testified before the grand jury, after receiving immunity from prosecution. Four of the players known to have testified previously underwent drug rehabilitation.

The six suspects who pleaded not guilty at yesterday's arraignment before U.S. Magistrate Ila Jeanne Sensenich were Dale M. Shiffman, 33, Jeffrey L. Mosco, 30, Shelby S. Greer, 29, Robert W. Mccue, 38, Thomas P. Balzer, 27, and Kevin M. Connolly, 27. All are from Pennsylvania.

Shiffman, charged with 111 of the total of 153 counts, is the only defendant not free on bail. William Lytton, Shiffman's attorney, argued in a 40-minute bail hearing yesterday that his client represented little risk to the community and would not flee.

But Sensenich sent Shiffman to Washington County jail without bond. Shiffman is accused of selling cocaine on each of the 79 days that the Pittsburgh Pirates played at home in 1983.

Sensenich scheduled Mosco's trial for July 8 before U.S. District Judge Paul Simmons. The trials of Shiffman and Greer were scheduled for July 22 before Judge Barron McCune. Judge Maurice Cohill will preside over the trials of Balzer, Connally and McCue. These trials are expected to be scheduled for September.

Players who have testified before the grand jury included the Pittsburgh Pirates' Lee Mazzilli, Rod Scurry and Al Holland; the New York Yankees' Dale Berra (formerly of the Pirates); Baltimore's Lee Lacy (also a former Pirate); the New York Mets' Keith Hernandez; Montreal's Tim Raines; Kansas City's Lonnie Smith, and Houston's Enos Cabell.