"The media's portraying me and my best friend and teammate to be malicious with our actions when we were really ... practicing safe practices," Plesac says.

Here's the deal ... Plesac ADMITS he and teammate Mike Clevinger broke MLB rules by leaving the team hotel and staying out past curfew during a road trip to Chicago.

"I went out to dinner with some buddies. We ended up going back to his place -- the same group that we went to dinner with ... and we opened up baseball cards," Plesac says.

"That entire night, dinner and hanging out at my buddy's place after, we were not with more than 8 people the entire night."

The problem ... obviously ... is that MLB had put strict rules in place to prevent another outbreak after COVID hit the Miami Marlins and the St. Louis Cardinals.

When news broke of Plesac's night out, he was killed in the media -- AND by teammates like Adam Plutko who felt he violated their trust and put the team at risk.

But, in a 6 minute and 30 second IG video, the 25-year-old pitcher argues he followed CDC guidelines that night and doesn't really understand why everyone is making such a big deal about it.

"You can't sit in a room all day," Plesac said.

Plesac says he's been doing research and vows to follow the rules moving forward -- but feels he's been "dragged across the mud."

He's adamant he'd never purposely put his teammates at risk -- citing his brother has diabetes and his mother is a nurse.

"I understand the significance of this illness and this disease and I know how important it is that we must follow certain procedures and guidelines to ensure safety for the entirety of the group."

Ultimately, Plesac says he's dying to get back on the mound and play again -- so he can "start shoving it up people" ASAP.