Armchair Strategist

Refers to someone who gives "ideas" about how things should have been done differently, or needs to be done in a better way, but has neither the ability nor the knowledge that required to deal with the case, and has never been in a similar scenario and never experienced in the like. Resembles the proverb: "After the ship has sunk everyone knows how she might have been saved".

"The marine's caption heard a lot of armchair strategist after he failed the battle".