why is this a blunder

( bd2 )

It is no blunder or mistake: other moves lose just the same.
The losing mistake is 8...Na5?

@tpr said ^

It is no blunder or mistake: other moves lose just the same.
The losing mistake is 8...Na5?

then why does lichess say its a blunder

"why does lichess say its a blunder"

• Because the lichess algorithm is not realistic.

@tpr said ^

"why does lichess say its a blunder"

• Because the lichess algorithm is not realistic.

doesent it use winning chanches instead of normal evaluation which should make it more realistic ?

"doesent it use winning chanches"

• The evaluation algorithm is correct.
  +1 used to be an advantage worth +1 pawn.
  Now +1 means an engine wins 50% of games from this position against itself.
  It is the lichess conversion from evaluation to blunder / mistake / inaccuracy that is flawed, i.e. inconsistent.

@tpr said ^

"doesent it use winning chanches"

• The evaluation algorithm is correct.
  +1 used to be an advantage worth +1 pawn.
  Now +1 means an engine wins 50% of games from this position against itself.
  It is the lichess conversion from evaluation to blunder / mistake / inaccuracy that is flawed, i.e. inconsistent.

how could it be better ?

@tpr said ^

"doesent it use winning chanches"

• The evaluation algorithm is correct.
  +1 used to be an advantage worth +1 pawn.
  Now +1 means an engine wins 50% of games from this position against itself.
  It is the lichess conversion from evaluation to blunder / mistake / inaccuracy that is flawed, i.e. inconsistent.

why is +1 50 lost 50 won, engines should be able to win most games from +1 or am i wrong

"why is +1 50 lost 50 won"

• +1 is 50 won, 50 drawn, engine vs itself.

"how could it be better ?"

• From between -1 and +1 to >1 or <-1 = mistake (?)
  From >1 or <-1 to between -1 and +1 = missed win (?)
  From >1 to <-1 or from <-1 to >1 = blunder (??)