I think you're right about the testing. Home runs have been down, but that's about all I follow.
I am a lifelong baseball fan and long time fantasy baseball geek. Scoring is way down. ERA is down across the league. Batting Average is down etc....
I know some pitchers were caught doing PED’s but if you look at the players, they no longer resemble comic book superheros in their builds...and because of that can’t take half swings at outside pitches to hit home runs.