San Francisco Giants legend Willie McCovey said a letter sent out by fellow Hall of Fame member Joe Morgan imploring that users of performance-enhancing drugs be kept out of Cooperstown was a shot at Barry Bonds.

"You're naïve if you don't think it was aimed at Barry," McCovey told the San Francisco Chronicle.

In the letter sent last month to voting members of the Baseball Writers' Association of America, Morgan -- who serves as the Hall's vice chairman and a member of its board of directors -- wrote "steroid users don't belong there."

"We hope the day never comes when known steroid users are voted into the Hall of Fame. They cheated," Morgan's letter stated.

No former players were mentioned in the letter.

Bonds played 22 seasons for the Giants and the Pittsburgh Pirates. He was a seven-time National League MVP and finished his career with 755 career home runs. In 2001, he hit 73 home runs in a single season. All are MLB records.

"I just think it's a sin [Bonds] is not in there," McCovey said. "If anybody deserved to be in the Hall of Fame, it's Barry."

The names of Bonds, Roger Clemens and Gary Sheffield -- who are on the 33-man ballot released on Nov. 21 -- appeared in the Mitchell report, a 409-page investigation into MLB steroid use overseen by former U.S. Sen. George Mitchell in 2007. Manny Ramirez, a 12-time All-Star and member of baseball's 500-home run club, retired in April 2011 after failing two drug tests in a span of three years.

"That letter Morgan wrote sure is not going to help Barry," McCovey said. "But I'm glad to hear a lot of the writers say the letter is not going to influence their vote, because I know a lot of it is aimed at him. I wasn't too happy about it."

As far as performance-enhancing drugs, McCovey added, "Guys took things ever since baseball existed."

"It may not have been steroids, but guys took things like those greenies and stuff so they could play the next day. You're telling me everybody is clean as a whistle? You played against guys who were doing the same thing he was doing, so what the heck?" McCovey added.

Bonds finished with 53.8 percent of the vote for the 2017 class, which was up from 44.3 percent in 2016. Players need 75 percent of the vote to be enshrined in Cooperstown.