I have seen guys get knocked out with 18oz gloves, that can definitely happen. I have seen guys get cut with 18oz gloves, that can happen too.
All I'm saying that anyone who says they have ever fought pro, and don't understand the difference between 18 or 16oz sparring gloves with headgear and 8oz or 10 oz gloves and no head gear, has never fought in their life.
It's a world of difference and it's the reason you have had great amateur fighters not do well in the pro ranks. Someone like Rigondaux for example, dominates people when he spars, because it's hard to hurt him with so much protection on and it's only a few rounds of sparring.
Yet he fights a guy in Marroquin, who is a good fighter but isn't on the same level and get's his bell rung not once, but twice in the fight. Small gloves, and no head gear is a completely different game.