This card is overpowered and should be nerfed. Slight +wall and -stock are fine, but this replacing effect...
There is full summon list.
U: Assassins, Corsairs, Hungry dead, Master thief, Pirates, Trickster.
R: Prince of thieves, Steelbeard. (Sellsword will be removed from it)
So we have ridiculously strong cardset (except sub-par Trickster). After this card you could get 2 Hungry dead, for example. Or, say, Master thief with its maximum potential, Steelbeard and Prince of thieves. Or some Corsairs which allow you try your luck with the same summon list again.
Pirate bay should summon any Brigands, not only non-common. Of course, it can be buffed in other aspects, for example, wall gain or cost.
What do you think about it?