I've played A LOT of Shaman and I understand how you can feel that it has all the tools, but fundamentally, it just falls short on so many levels that makes it just not a good control deck.
Last season I ran Control Warrior and got to rank 5 fairly easily, but when I've tried to climb with Shaman it's been a real struggle.
There's a number of ways that Shaman just doesn't perform up to the level of Control Warrior:
Hero Power. Control Warrior's Armor Up! gives you inevitability - "the strategic consideration that, all things being equal, one deck will beat another given enough time." Face Hunter has to get a ridiculous opening hand and good draws to win, or else CW just has inevitability since its hero power essentially negates Hunter's and Face Hunter just can't match the CW in the late game. Shaman's Totemic Call, on the other hand doesn't mitigate damage nearly as well. Sometimes you need a Stoneclaw Totem to stay alive, but get Wrath of Air Totem instead. A 0/2 with taunt might mitigate 2 or more damage from an attacker, but the other three totems can be ignored and allow your opponent to just attack you directly.
Healing Shaman's healing just isn't as good as Warrior's. Healing Wave heals for a bunch, but Shield Block is almost as good and draws you a card. Warrior gets free healing with the hero power. Armorsmith gives it more healing. Shieldmaiden is a big body with lots of healing. These last two allow Warrior to develop its board AND heal up. Healing Wave doesn't stop attackers, only gets you out of range this turn. Antique Healbot can be in a Shaman list to help you against Hunters, but a 5 mana 3/3 just isn't the same as a 5/5 for 6 that Control Warrior has. Shieldmaiden can take down Sludge Belcher, while Antique Healbot does not. One of the most important things, though, is that Justicar Trueheart means that Control Warrior heals for 4 a turn for 2, using no additional cards. That just puts you out of range of many decks. Freeze Mage and Face Hunter just hate it when you play her.
Removal. Control Warrior has removal that works well early AND scales well into the late game. Execute and Shield Slam can both take down early minions or late ones. Brawl can remove most of your opponent's minions, whether they're small or big. Earth Shock, Crackle, and Lightning Storm all have issues dealing with large minions that isn't compensated enough by Hex. Fiery War Axe and Death's Bite both can take down multiple minions, letting you get card advantage, while Rockbiter Weapon and Lightning Bolt are both one-time use removal.
Card Draw Ancestral Knowledge overloads you and Mana Tide Totem usually replaces itself unless you can protect it well. Shield Block and Slam are both more flexible ways of "cycling", even letting you trade them late game for another card. Acolyte of Pain can get you two for one, if you play it right, and sometimes can even do better than that if you can trade it for something like a damaged Knife Juggler in an attack after a Death's Bite's Deathrattle.
Overload This is really THE thing that's holding Shaman back. Control Warrior can curve out with a game plan like Fiery War Axe, Bash, Death's Bite, Brawl, Shieldmaiden, Dr. Boom, Justicar Trueheart (Tank Up!). Contrast that to the awkward position that Overload can cause: Rockbiter Weapon, Haunted Creeper, Lightning Storm, Totemic Call, Crackle + ??, Sludge Belcher. Twice in the Shaman game we're forced to play off curve (turn 4 and turn 6). Ideally, those would be great turns to play Piloted Shredder and Fire Elemental, but Lightning Storm and Crackle caused issues.
One alternative to the first and last problems is to try to use Totemic Call as infrequently as possible and to use little to no Overload cards, but then the deck is just weaker overall and still feels like a weaker version of Midrange Druid without the inevitability of the Force of Nature Savage Roar combo or Control Warrior without the better removal and better finisher - Grommash Hellscream is better than Al'Akir.
