Hidden Attributes

Tear Height
Tear height is a hidden attribute that determines how far above the ground tears travel, and in practice increases effective range. Very high tear height makes Isaac's tears' "cruising altitude" so high they can cross over obstacles as if they were spectral, but they won't go through the room walls. Once the tears fall down, they will start hitting obstacles again. This compounds with the starting height from the range stat.

Other

 * In co-op, Long Baby will occasionally briefly increase range, shot speed, and tear height. Dark Baby will occasionally briefly increase all stats, including tear height.
 * starts with -1 tear height, though the stat does not affect his short-range Brimstone.

Knockback
Knockback is a mechanic that determines how far an entity is pushed back by a certain force.

There are two kinds of knockback: directional and circular.

Directional Knockback
This knockback comes from Tears, most notably Isaac's. The knockback force is determined by the speed and direction of the tear, which itself is determined by Isaac's movement and stats. For example, Ring Worm does not increase the knockback stat, but does affect knockback as the tear's speed hits extremes of very fast and very slow; hitting enemies with the fastest moment of its arc applies significant knockback. (Needs research and confirmation)

Directional knockback affects most enemies, including bosses (except for stationary ones like Pin or Round Worm). Items (both trinkets and pickups) cannot be moved by tears, except for bombs placed by Isaac.

Circular Knockback
This knockback is a little shockwave that's emitted at a certain radius in all directions, most prominently from explosives, like Bombs. Certain farts also create a (non-harmful) knockback. Some enemies, like the Fatty, can fart, and Isaac can also do so with the.

Pickups (including chests) are affected by circular knockback; items, however, are not.