Black – Pips 128 (+96)
Black to Play 4-5
But in backgammon, practically every good rule has a few exceptions. Keeping your 6-prime intact is very important when you have little or no chance of picking up a second checker. In that case, you use the ‘slot-and-cover’ method to methodically roll your prime around the board. Once your opponent leaves a new blot exposed, however, you’re going to need to make an effort to pick it up, and that may involve breaking your prime, sometimes in very odd ways.
In this position White has exposed not one but two checkers in his home board. If Black makes a straightforward play like Bar/20 19/15, White will get a chance to roll a deuce and consolidate his position. If Black wants to hit a second checker, he needs to strike now, either with Bar/20 7/3* or Bar/21 8/3*. Either play may force White to hit back, giving Black a shot at the two loose White checkers.
How important is hitting a second checker? Very. If Black closes out just one checker, and arranges his spares on favorable positions, he’ll be a bit over 40% to win. (White already has nine men off, remember.) But if Black can hit two checkers and close his board, he’ll be about 88% to win with his spares well-placed. (In fact, after hitting two checkers he won’t even need to close his board to double. His proper doubling point will come much sooner.) That’s a huge swing, so Black should be willing to take big chances to get the second checker.
Both hitting plays are good. Hitting with 7/3* leaves more shots (18 to 16), but this isn’t a disadvantage because Black wants to be hit before White has a chance to consolidate. To see which hit is better, we need to notice a subtle tactical point. Imagine that White now enters from the bar and jumps, hitting only Black’s blot in the outer board. (This happens if Black played 7/3* and White responds with 6-1 or 5-2, or if Black played 8/3* and White responds with 6-2.) If Black played 8/3*, he now has 20 return shots: all ones and threes. But if he played the correct 7/3*, he has 27 returns: all ones and threes, plus 6-6, 6-2, 5-2, and 4-2. That’s a big swing on White’s most dangerous throws, where he actually gets to Black’s outer board. Train yourself to actually count shots in critical variations, and you’ll pick up some subtle plays that others would miss.
