The Chicago Cubs, who dug deep to keep their free-agent pitchers, have saved $300,000 by winning their arbitration case with first baseman Leon Durham.

The Cubs offered Durham $800,000 for the 1985 season. He sought $1.1 million. Steve Goldeberg, a Northwestern University law professor, ruled yesterday after hearing the case Monday.

"We felt that Leon was not at this stage in his career a million-dollar player," Cubs chief executive Dallas Green said.

Washington attorney Robert Dufek said he and another Washington lawyer representing the Cubs, Frank Casey, stressed that, at $800,000, Durham would match Minnesota Twins first baseman Kent Hrbek's 1985 income. Hrbek's productivity stats for 1984, and his career average, were all higher than Durham's.

Dufek said the decision should not be read as beginning a trend. "The really top stars of the game are hard to beat in salary arbitration, generally," Dufek said . . .

The Toronto Blue Jays probably thought so, signing pitcher Bill Caudill to a five-year agreement worth at least $6.5 million just minutes before the reliever was scheduled for a salary arbitration hearing. Caudill's agent said the contract was worth more than $1.3 million a year -- the figure Caudill would have demanded at the hearing . . .

Atlanta Braves right fielder Claudell Washington ($700,000 a year) has been charged with suspicion of possessing cocaine, a felony in California. Washington had treatment for drug dependency after the 1983 baseball season and was a National League All-Star in '84. Now, he is out on $3,000 bail, awaiting arraignment within 25 days. His 1985 Jaguar was stopped by a Walnut Creek policemen who said it was weaving.