Not only are there tons of fast mana floating around, but there are usually tons of cheap creatures and tokens too
While it's true that this opens you up to potential blowouts when they wipe the yard with cards like Bojuka Bog or Tormod's Crypt, remember that we're going to be drawing extra cards, too, and we'll be putting cards into the graveyard on most turns, meaning we can recover from a Bog (or Draugr Necromancer) fairly quickly
Though other black tribes such as rats provide access to more swarm-based strategies, few of the colors' tribes are as diverse as vampires
Derevi decks win by establishing a hard lock and then slowly chipping away at opponents life totals with an army of small, evasive creatures
Differentiating between the top couple cards in the set is more important to me than judging whether some niche sideboard card is C or D tier
Bayou Groff is probably more of a 5-drop than a 2-drop here, so my curve is a tiny bit higher than it looks, too