The names were probably less of a clue than the fact that they pounded pain rods into their brains to turn themselves into raving psychotics on purpose.
The World Eaters definitely stood out as being "Legion most likely to turn on the Emperor like a rabid badger" way before Lorgar took his spiritual journey into Crazyville. Angron was the only Primarch to fall to the sales pitch of "Hey bro, wanna go kill Dad?"
Lorgar was understandable, I feel. E was quite deliberately and sensibly trying to create a secular Imperium. The very fact that the Word Bearers took their reprimand so badly reinforced how out of line they were. And there was no way to predict that they'd do a complete 180 and turn to Chaos... well, except for that whole precognition thing, but whatever. My point is that Erebus is a dick.
But yeah, Angron is a glaring, gaping hole in E's record of judgment. Lorgar spent much of the Betrayer novel wondering just what the hell He was thinking plucking Angron from his homeworld, handing him a Legion, and then essentially washing His hands of the matter. There was way too much that could have gone wrong. And it did.