Yeah, deckbuilding uses a mathematical proportion, so if you play more than 60 cards, you lower your chance of seeing a particular card in a given game, thus lessening how effective your deck is. For sideboard, I'd run Guttural Response and perhaps 1-2 Eyes of the Wisent as well. You could move the Finks to the sideboard, and only board them in against heavy aggro or aggressive burn decks.