Board-A-Match is a form of scoring used in team games (usually only at major National Championships). Each team (of 4 or 6) has a North-South and an East-West pair. They play against their counterparts from the other team. Typically each team plays only 2 or 3 boards against another team. Then the change is called and the East-West pairs move to face a new team. Only at the end of the entire session can teammates compare scores.
Instead of the more common "IMP" comparison (where, for example +620 at one table is compared with, say down 1, -100 at the other table for a 720-point swing converted to 12 IMPs), the BAM score is more rudimentary. The board is scored as either a "WIN" a "LOSS” or a “TIE (PUSH)”. If the N-S pair is +620 and the E-W pair at the other table is +100, the result is "1" -- a full win. If a team is -800 East-West at one table and also -2,000 by the North-South pair at the other table, it is simply a loss or "0." If both tables achieve the same score, say +170 at each table, it is a tie and 1/2 for each team. At the end of the session, each team adds up its ties (worth ½ each) and wins (worth 1 each). If 26 boards are played, an average session is 13 points. Whoever gets the most points in the event is the winner.
You can win a board in BAM by the smallest of margins. If the N-S pair is +130 in a diamond partial, and their counterparts play in 2NT, making 120, they would get a full 1.0 (WIN) on the board! If it were IMP scoring, this scenario would produce a nothing board – 0 IMPs (since 0-10 on the IMP scale isn’t worth even 1 Imp).
Very few tournaments use this form of scoring, yet many experts consider it the “purest” form of the game. The major fall National Championship Team games (Open BAM and Reisinger Teams) are Board-a-Match. Recent Buffet Cup events (USA versus Europe) have also tried the approach. The organizers thought the scoring would be the easiest for the general public to understand. A board is played and the team who gets the highest score wins. No IMP scale or math needed.
In matchpoints, overtricks (and extra undertricks) are important as the small differences count for each comparison at every other table. In IMPs (Swiss or Knockout), the focus is on making the contract (overtricks are of small value). Vulnerable games are strived for as 620 against 170 yields a bountiful 10-IMP win. What about BAM? It is more like matchpoints than IMPs. If you are in what seems to be a normal 4 (where you are pretty sure the other table will also be there), you would place importance on overtricks. Consider this layout:
On a club lead, at IMPs, you wouldn’t risk the finesse. If the lead is a singleton, you risk defeat (RHO wins the king, issues a ruff and gets in with a diamond for another ruff). At matchpoints, you would finesse, trying for 2 lucrative overtricks. As long as West has the K, you can win in hand, draw trump, repeat the club finesse, discard a diamond on a club and make 6. At BAM, you’d expect the other table is in the same contract. You should take the finesse (risking the contract). If the lead is a singleton, the other declarer will likely get the same lead and also finesse. Meanwhile, if West has led from the K and you go up with the ace, you will probably lose the board. Perhaps West has:
54 A43 K10876 K42. For whatever reason, he chose a club lead. If you win the ace and your counterpart gets, say a diamond lead, you have lost the board.
Suppose South winds up in a vulnerable 3NT (don’t ask how) here:
Spades are lead and declarer sees 10 sure tricks (1 spade, 5 hearts, 2 diamonds and 2 clubs). He can cash out for +630, but that would probably lose the board. Likely the other table is in hearts, where 11 tricks are easy (only a diamond and spade will be lost). In 3NT, declarer should risk the club finesse. If it wins, he likely will win the board (+660 against +650). If the club finesse loses, he might go down (or at best will be +600 if spades are 4-4). But, losing to +650 by being +630 or +600 or -100 is all the same. The risk should be taken. At IMPs, of course, declarer wouldn’t dare risk the club finesse. (At matchpoints, he probably would also take the club finesse; matchpoint strategy is very similar to BAM strategy).
At BAM, the partscore battle can be intense. Doubling a partscore is more prevalent than in any other form of scoring. Even at matchpoints, tight doubles of partscores risk bottom boards and are often avoided. But at BAM, if a player suspects his opponents have already out-competed him, a penalty double is often a no-lose proposition. Consider both sides are vulnerable and opener holds:
KQ1076 KJ2 K102 32. His 1 is raised to 2 (“constructive” about 7+ to 10). This is passed around to LHO who after long thought, balances with a double. Responder redoubles to show extras. RHO removes to 3. At IMPS, you could just hope to set them and collect 100 or 200 (not risking -730). Even at matchpoints, it isn’t clear to double and risk a bottom board. But at BAM, you should double. If 2S was making (+110) and you collect only 100, you will likely lose the board. Meanwhile, if 3H is a make, you probably are losing the board anyway (from the tempo, you can tell that LHO’s balance was marginal and your teammates might sell out to 2S). Your double has a big upside; it could turn a losing +100 into a winning +200, whereas passing risks + only 100 for a loss. Turning -140 which is probably a loss into a sure loss by doubling doesn’t have a big downside.
Game and Slam bidding is not a big deal. If game (or slam) is at least 50%, then it is worth bidding. There isn’t the need to push for close games (as at IMPs).
A team can have a very large percentage score in a session. With 26 deals played, a score of 18 or even 19 isn’t too rare. Even 20 (77%) or more is not unheard of. This is due to the nature of a “1 top” on a board, which creates the possibility of a huge game if the team scores mesh well. Speaking of “mesh,” you will often hear a team bemoaning a “poor mesh.” For example, on Board 1, the N-S Pair is +790 (expecting a sure win) but their teammates have also had a huge result (+500) on the same board. The team has “double-won” the board but still gets just 1 point. On Board 2, one pair is +90 for skillfully making 1NT. But, their counterparts scored 100 on good defense. Though lost by “only 10 points” the board is scored a “0.” On that 2-board round, each pair would have expected a sure win and a “maybe.” They end up with just the 1 point.
This form of scoring requires lots of stamina. You never know when a trick can be the difference between a win and a loss. At no moment can you let up, even though lots of the tricks won/lost will be totally irrelevant. If you are fighting hard for an overtrick in 2, but your counterparts are in 4, your result won’t matter (the board is already won or lost at the other table). Yet, the other table might be +120 on your cards and your effort to turn 110 into 140 will be worth everything!