You exaggerate MangaEnvy's position.
No, I don't.
You exaggerate AnimeEnvy's though. He had like 15 minutes of screentime in the entire series there.
Being "major" in a story has nothing to do with the character's position in the chain of power in the bad guys' group.
In the manga he's responsible for both starting the Ishval war and killing Hughes, which are easily two of the biggest causes of sorrow and suffering for the good guys. He's also the most prominent homunculus along with Wrath, having by far the most screentime and appearances. So yeah, he's a major antagonist. Period.
Also it's beyond moronic to fault him for losing against Ran Fan when it's obvious that if he had fought at full power he would've crushed her like he did Ed and Ling.
And the only reason he got 'OWNED' by Marcoh was because he was ordered not to kill him. He beat him 1 minute into the fight after catching him with his tongue and could have killed him right there and then.