Hmm... now that I think about it, was is the worst uncommon? Typical Beanstalk is pretty bad, but is it the worst? Let's take a look at the worst ones for each class-
Potato Mine- not enough damage to deal with some 1-drops, requiring destruction means zombies can still chump block plants behind it (Banana Bomb lets you clear the way most of the time)
Sizzle- Not a good power to Sun ratio
Typical Beanstalk- Poor stats, mediocre ability, outclassed by every Cosmic card. Even Cell Phone Zombie is cheap enough to chump-block. Yeah, it's probably the worst.
Vanilla- This is why mediocre all around isn't good. They could have done something cool if textless cards had soem sort of synerygy- nah, nevermind. Maybe it could do a "Silence" effect from Hearthstone.. eh.
Water Balloons- Once upon a time, this was actually included in one of the highest-rated community decks. It let Chompzilla deal with Fishy Imp. Man, times sure have changed.
B-Flat- The Yeti Lunchbox used to be worst, but it barely squeezes ahead now thanks to its new Pet Synerygy. Same thing for Goat. B-Flat isn't reliable, but it's actually the best card on this list (Beastly has some good Uncommons).
Pirate's Booty- It needs three zombies in play just to be better than Fun-Dead Raiser.
Cakesplosion- Just nothing special. They didn't even bother to make it Gourmet.
Space Janitor- Its ability implies that there will be a card to remove at the start of the turn, which is less likely than the start of Zombie tricks for cards like Rolling Stone.
Firefighter- This card always had some trouble, requiring you to beg that there would not only be a zombie you want bounced, but that the Plants wouldn't remove it before tricks. Secret Agent does this much better.
Oh, and one more thing: Duckstache isn't that bad. Sure, the Mustache synergy isn't as good as Berry or Imp, but conjuring one every single time it does damage? In a class that promotes bonus attacks?