Green’s Dictionary of Slang

(US) to criticize with the benefit of hindsight; usu. as n., Monday morning quarterbacking.

1943		Life 27 Dec. 4: It's pretty bad when we start worrying about what to do to Germany when it is still giving the world a hell of a battle and probably will be for some time. Why not win the war first and do the Monday morning quarterbacking later?
1950		N.Y. Times 22 Oct. VII 1: This Monday-morning quarterbacking is balanced by the fact that he knew the Allied course was wrong even in Italy .
1959		Jet 24 Dec. 22: Taking care of the children now is the problem and should not be influenced by Monday morning quarterbackin.
1962		R. Tregaskis Vietnam Diary 43: It’s easy to do Monday-morning quarterbacking, but the Rangers [...] reported that the VC were going to move in.
1971		Seattle Times 17 Jan. A7: Shaw criticized ‘Monday-morning quarterbacking’ of field operations from Washington [HDAS].
1980		Field & Stream Sept. 79: But yearend totals and all the Monday morning quarterbacking in the world do not and cannot answer the overriding and nagging question [etc].
1994		R.J. Wicks Hbk Spirituality for Ministers 1 18: Monday-morning quarterbacking is not totally without its value. It fills hours pleasantly. It builds up camaraderie [...] But it cana lso deceive us.
2002		Guardian 18 Sept. 🌐 Equally, he was critical of what he called ‘Monday morning quarterbacking’, which is an American expression for hindsight.
2021		T. Pluck Boy from County Hell 346: [H]e Monday-morning quarterbacked him after he read the reports of the attack that cost Junior the leg.