Depends on the matchup.
Paladin mirror matchups will burn a consecrate as soon as muster for battle is played.
And when they actually need the consecration, they're probably screwed. Trust me, they aren't using consecration because they want to. They are making a bad move because they are afraid, and often over-reacting, to the possibility of a strong quartermaster turn.
But sometimes playing around a card actually makes you lose because you literally just spent 4 mana to get rid of like half the power of a 3 mana card. Later on in the game when they have 1 or even 0 consecrations left, they will look back and lament the wasted potential of a consecration because they delayed the usage of a single card.
Granted, I've been there, done that. You really really don't want to play consecration on turn 4, unless a player somehow over commits to the board and at high level play that almost never happens. I think the times I am okay with consecration on turn 4 is when they have a knife juggler + more, cause 1. I hate that bugger, and 2. knife juggler's damage output is just too much when it goes unchecked.
edit:
Also if it's a rush deck, you want to keep a consecrate. I usually keep one for Mages and Hunters.
I recently put Frostwolf Warlord back in my deck because I keep complaining how I don't have enough heavy dealing minions. Works very well.
You can have a pretty powerful card at Turn 5.
It depends on the rush deck tbh. Yes you want consecration but you don't necessarily want it from the beginning of the game. Paladin wants zombie chows, shielded minibots, harvest golems, and basically sticky/proactive minions against aggro decks.
Consecration vs face hunter? Usually not good enough. You clear their board and all they do is hit you with charge minions and weapons. Then next round you don't have any board yourself, because all you could do is consecrate, and you're staring a 3/1 minion who already dealt 3 damage and you're going to take another 3 damage next turn because of your decision to consecrate. Consecration just is too slow against face hunter to keep in your mulligan, most of the time. If you already have a zombie chow or minibot, maybe consecration is ok. Going first or second makes a difference too.
As for mech mage, I think I talked about this match up with you before. Again you really want proactive minions. They don't have a lot of minions that consecration can just wipe off the board without you having damaged them already.
Frostwolf warlord... is okay... in a budget deck. But you'll eventually replace him.
