The key card is present but its support is thin.
Prioritize useful support such as Featherbrained Filcher or Dream Beavers.
Attack with Filcher, return it for sneak after blocks, and collect its Food. On a later turn, replay the flyer to threaten sneak again.
Your deck already enables the plan but is losing the early turns.
Take a castable early creature or efficient answer before a second expensive payoff.
Sneak ends before combat damage. You cannot deal damage with the original attacker and then replace it for another normal damage hit.
The support is missing
Favor independently useful creatures and interaction if the narrow support does not arrive.