an average 1 drop is either 1/1, 1/2, or 2/1
an average 2 drop is 2/3 or 3/2 but it is not uncommon to find 3/3 or 2/2 2-drops
an average 3 drop is either a 4/5 or a 5/4. it is not uncommon to find 3 drops with stats less then this when they have good effects, UDE does this to make the character balanced. Some 3 drops that have above average stats such as Ubu and Wolverine are that way because they have loyalty. It is also not uncommon to find a 3 drop with virtually no effect, or flight, or ranged that is a 5/5. examples would be space bears and thing.
and average 4 drop is either a 5/8, a 7/7, or a 7/8. Some 4-drops, but not many, also have high defense and low attack such as fiero which is a 3/9. Something to remember at this point is that a character's stats are usually a result of their effects and that a character with low stats is not nessisarily a bad character.
An example would be chosing Hawkeye 4 drop over both Iron Man 4-drop and Thor 4-drop. Hawkeye, a 5/8, clearly pales in comparison to thor at a 7/8 but Hawkeye is a reservist, is amazing against squadron and anything off curve, and is great on the defense as well because on turn 4, if your opponent has the initiative, when he's attacked, he'll basically stun 2 characters due to his ability and high attack. Iron man is usually chosen over thor also because of his ability, one attack point is not enough to chose thor over iron man.
a typical 5 drop has 9/9, 9/10, or 10/9.
a typical 6 drop is either 12/12, 11/13, or 13/11
i'm sure you get the point by now.
Hope I helped :icon_mrgr