No one by that name shows up on the Red Sox roster or any MLB team roster.
However, there was a Dan Johns that pitched in the Montreal Expos' minor league system (Gulf Coast League and New York-Pennsylvania League teams) in 1977 and 1978.
Dick Radatz
The only Boston Red Sox Pitcher during the 1990s who is named David is David West.
"There is a famous pitcher for the Red Sox named Josh Beckett. He is from Texas, and he was traded from the Florida Marlins to the Red Sox team in 2004."
cy young, the Boston red sox pitcher. he now even has a pitching award named after him.
Clay Bucholz
Rico Petrocelli was the Boston Red Sox pitcher in 1975.
Definitely Jon Lester
Keith Johns debuted on May 23, 1998, playing for the Boston Red Sox at Fenway Park II; he played his final game on May 26, 1998, playing for the Boston Red Sox at Fenway Park II.
I'm not sure what pitcher you are talking about, but the Red Sox pitching rotation is Josh Beckett, John Lester, John Lackey, Clay Bucholz, and Daisuke Matsusaka.
Brad Penny is not with the Boston Red Sox. I believe he is now a pitcher with the St. Louis Cardinals.
Mike Ryba, a pitcher, wore #20 for the Red Sox between 1942-1946.
obviously its Cy young[who else]