Do we want this big of a roadblock at common? So far 4 toughness is looking to be the magic (hehe) number for the set with regards to blocking and not dying so this'll stick around for quite a while.

Perhaps something in a little different direction, like...

Deathfang Rattler
Creature - Snake [Common]
Deathtouch
Prevent all damage ~ would deal to Artifact Creatures.
2/1

Deathfang Rattler fills a similar purpose to Ghoul Overseer but isn't nearly as oppressive against aggressive decks and actually fits better in the archetype, b/c it's an early beater the opponent doesn't want to block then late game, when they have 1 or more artifact creatures, it becomes fodder for exploit triggers and valuable Trash enabler.

three thumbs up for deathfang rattler

Since Prophet's "Scorpion" is already in the skeleton, I approve Deathfang Rattle. Just a note though that now black has 3 creatures with a single point of toughness. This is sort of a weakness against tokens and thopters. The last few creature slots should probably have extra toughness gravy.

I agree with you on the toughness front, I think it'd be fine as a bear (2/2).