Arguably the most overrated card I've found in this archetype in order,

1) Aether Vial, I'd play with Merrow Reejerey before I cut Merrow Reejerey for his dissynergy with Aether Vial. Aether Vial is the card that has dissynergy with Merrower Reejerey and not the other way around, and I haven't found a reason to "cheat" costs on a flat curve when hard casting Merfolk with a Merrow Reejerey on the board can untap a land and "cheat" costs that way.

2) Standstill, with out Aether Vial and Mishra's Factory, Standstill is awful.

3) Curiosity, just splash for Dark Confidant instead.

4) Rishadan Port, the deck has enough mana denial with Wasteland, Stifle and Merrow Reejerey as it is, and I'd rather sit back on Counterspell mana than fiddle with my opponent's lands.

5) Reef Shaman and Tidal Warriors, while they're very synergistic, they're also very unnecessary. You can do a lot of damage to the opponent with just Wasteland and Stifle, and as long as you are playing Umezawa's Jitte to establish a clock or Counterspell to protect your board, you can bring the game home against control. Against aggro, you want to take them on toe to toe with 8 pump creatures and Sygg, River Guide instead of racing with evasion. You aren't faster than other aggro decks, so racing is often a moot point.

6) Ponder, frankly, you don't want to drop your guard with Stifle, Spellsnare or Counterspell for a tempo sink in a tempo deck.

7) Balance/Top, with out 8+ cantrips and/or Trinket Mage it's inconsistent against aggro-control and worthless against aggro, which is where you need the most help.

8) Mono-U, you can easily afford to splash a color and both white and black have a lot to offer.