For example I looked up Kenyon Martin today. I remember him being an all-star so I figured he must have had multiple 20/10 seasons. Turns out he never averaged more than 17 ppg and only got 10 rpg one season.
Muggsy Bogues surprised me positively. I thought he was just a role player like Early Boykins. Turns out he had several seasons averaging over 8 apg and a couple seasons averaging over 10 apg.
Peja Stojakovic. Dude was right up there in points per game for a couple of seasons in the mid-2000s. I only saw the tail end of his career and never knew it.