This is another factor I just can't quite get behind and agree with. If you've lost board control and can't get minions on the table long enough to use Bloodlust chances are high you're fucked either way. I can't think of a card (that shaman has access too), at all, bar Deathwing that could swing it back around in your favor.
If you've lost board control and can't develop a board, then every card in your hand is a dead card.
Not really no. You can still play a threat, and they might spend their entire turn/board to clear the threat you played. But if instead you have a Bloodlust, you can't do shit. Now optimally, you don't run in a situation where the only card left in your hand is Bloodlust, but Shaman is notably garbage at drawing and keeping a full hand if you're not getting insane value out of your cards, and Bloodlust really doesn't help much with that. If you draw a Belcher or Loatheb instead(to keep the 5mana thing going, though you'd probably replace it more with like Cairne or Sylvana or a Fire Elem if you don't have 2 instead), it's going to be a lot more impactful than if you draw Bloodlust and you don't already have a board presence ready to use it. Now if you do, you might just win the game.
It's a gamble card. It can and will definitely work sometimes, but sometimes it'll also be completely useless. In general, when building a deck, you want to limit cards which are potentially useless to a minimum, which is why you don't run 4silences in every deck even though silence can and will win you games very often and in most games, you could actually make use of 4 silences. But in some games, you will barely make use of one, and so most decks only run one or two silences. Same reasoning with BGH(though in tournament play, 2BGH can be a valid choice if you expect handlocks and warriors all over the place).
One Bloodlust is fine though especially if you don't have access to all the big legendaries and shit. Eventually though, you'll pretty much phase it out unless you're doing a gimmick shaman thing(like murloc shaman, then fuck yeah do bloodlust, it's murlocs).
