What's The Biggest Possible Comeback?

     If we don't include a blunder that leads to a checkmate, what is the furthest
behind a player can be according to Computer Analysis and still make a comeback and win or at least draw?

     For example, -1.00,-2.00, and so forth.  In other words, is there a "Point Of
No Return" that exists as a game is analyzed when it is clear the game can't be won?

 

Define blunder, because to a GM a blunder might be to allow an uncompensated isolated pawn.

The point of no return in engine talk is (+)(-)1.70. I heard somewhere (chessbase I think) that 1.70 is the magical number that you call "decisive advantage". If you see that number in any modern engine's evaluation of a position, (given that it is not a known theoreticaly drawn position) the computer will win the position against itself in 100 percent of the cases. I haven't heard about a drawing threashold yet- I think there won't be because draws are often times too complex to define in numerical terms like that.

I was thinking of a loss of a piece as a blunder but it is true at the higher levels
a pawn can make the difference.

Another exhibition of my ignorance, at which I could take anybody on blindfolded