After a commited blocker was killed, he didn't leave a blocking "ghost" card - is this a new mechanic?

I've just played a game, where I put a blocker and commit it, then the opponent kills it with a vengeance and his attacker was able to reach my Nexus : is this supposed to happen ?

In all my previous games, this action - killing a committed blocker - creates a ghost card which still blocks the attacker.

In this game, however, there was nothing left and the attacker dealt his damage.

No access to the action log of past games as far as I know, so no possibility to show you.

The only valid case for this behavior would be when blocking a unit with "Overwhelm".

When you block a unit with "Overwhelm" the pass through damage is still applied. There is no need for a ghost card to take your units place as the ghost card would have a toughness of 0 and thus the full damage is passed through.