Sire Den. isnt even in top meta decks played in standard. Those complaining are in low elo or hardstuck. Check out HSreplay.net > Meta tab at top of page > you can see the tiers or you can go to sort by Class decks and see win % that way.
Sire Den is a card that takes a lot of turns, minions to set up. It's not that great. Same people complain about Sire probs complained about C'thun...
Imp Warlock, Beast Hunter, Relic DH, Control Shaman, Ramp Druid, Control Paladin, Thief Rogue, Spooky Mage, Evolve Shaman, Taunt Druid. All of them play it. If you compare it to C'thun, you have no idea what you are talking about
At legend Thief Rogue, Ramp Druid, Relic DH, Spooky Mage, Control Paladin, Control Shaman alone are more than 50% decks of the meta, at top 1k legend - more than 60%. That means every second deck you face plays Sire.
You might not play at legend, but still at all ranks the most popular decks are Thief Rogue, Ramp Druid, Imp Warlock, Spooky Mage, Beast Hunter, Aggro Druid, Relic DH. In Top 7 most popular decks only one does not play Sire!
Imp Warlock, Beast Hunter, Relic DH, Control Shaman, Ramp Druid, Control Paladin, Thief Rogue, Spooky Mage, Evolve Shaman, Taunt Druid. All of them play it. If you compare it to C'thun, you have no idea what you are talking about
At legend Thief Rogue, Ramp Druid, Relic DH, Spooky Mage, Control Paladin, Control Shaman alone are more than 50% decks of the meta, at top 1k legend - more than 60%. That means every second deck you face plays Sire.
You might not play at legend, but still at all ranks the most popular decks are Thief Rogue, Ramp Druid, Imp Warlock, Spooky Mage, Beast Hunter, Aggro Druid, Relic DH. In Top 7 most popular decks only one does not play Sire!
So yes, Sire is too good and too popular.