Former relief pitcher Tom House tells Ron Kroichick of the San Francisco Chronicle that performance-enhancing drugs and steroids were widespread in baseball in the 1960s and 1970s. House pitched for eight years (1971-78), including the Red Sox in 1976 and 1977.
House: "I pretty much popped everything cold turkey. We were doing steroids they wouldn't give to horses. ... I tried everything known to man to improve my fastball ... [We used to say] we didn't get beat, we got out-milligrammed. And when you found out what they were taking, you started taking them."
House estimates that six or seven pitchers on every staff were "fiddling" with steroids or growth hormone. I can only assume that a lot of the hitters on every team were also fiddling, if only to keep pace with whatever advantage they believed the opposing pitchers might be getting.