Why move 17 costs half the game?..
Half the game is maybe a bit too much, but it is a heavy blow for black. After P 6 you have two weak two stone groups you have to look after. Almost never a good idea to let your opponent connect.
Put a variation in your game chat.
Thanks, I’ll check that!
Half the game I meant AI went from 52% to 1%. Ouch.
Here are some reasons I can think of:
- White captured a stone.
- White made an excellent shape. See https://senseis.xmp.net/?Ponnuki
- White connected stones from two groups together.
- White separated Black into two groups.
- The lower of the two black groups can’t survive.
- White smothered many of Black’s liberties.
- White removed bad aji. See @Atorrante’s variation for one possibility lost.
That’s a whole game!
52% means pretty even
1% means destroyed
While if you look at score it’s just 15 points. I can make mistakes bigger than that!
In AI’s mind a 15 points advantage is fairly enough to be sure to win.