A poison, to me, is someone who severely hurts you in the shooting struggle, the possession battle or in the fouling game. The worst poisons hurts you in all 3. Most poisons hurt you really bad in one and somewhat in another. They don't ever really help you somewhere... Take McGinnis, for example. Yeah, he gives you some boards... but holy crap look at the TOs. We're not talking Wilt TOs, either, where the boards & efg% and (lack of) fouls totally eclipse the TOs, we're talking TOs that eclipse everything. Oh and then fouls. Fouls galore!
Elgin Baylor is someone who is borderline poison. Yeah, his high usage and mediocre fg% hurt you - a lot. But if you play him at SG - or even PG - his rebounding prowess is huge. You think he turns the ball over a lot, but when you really focus on the actual %s, he doesn't. He moderately hurts you in one area, but really, really helps you in another. A player like this will be a superstar find in this type of league. I think 'Nique is a case like this, only not quite as extreme.