mike777, on 2014-January-27, 22:35, said:
Surprised so many experts feel the first double is so very wrong.
I'm not sure anyone is claiming that it is "so very wrong". My reading of other bidders (rather than doublers) is that it is antipercentage because it misleads partner about the nature of your defensive prospects when they want to sit a reopening double. The club void reduces the defence's options considerably while only increasing partner's expected club length a bit. Partner could easily be looking to pass a reopening double on this auction so it needs to be taken into consideration when choosing the action.
It's clear that a double can work well - it's the best way to a better major suit partscore for example. But partscore accuracy at IMPs isn't a high priority, and you need to consider what partner might do after your action. Think of the hands partner can have:
1. A weakish balanced hand. Here 2D is likely to be the long-term winner since you don't have to worry as much about losing control on the hand. But it probably doesn't matter much what you do.
2. A weak unbalanced hand. Double will win here since you'll find a real fit.
3. A moderate hand with no previous bid. Double can cause problems for partner who may feel the need to jump to show their strength. That should probably be fine, but still puts you one level higher opposite your moderate hand. Additionally, you don't have a minimum so you might bid again and get too high. These hands can creep up without either partner doing anything clearly wrong. 2D avoids this, and now if partner does move it's clearer that looking for game is a reasonable choice.
4. A moderate hand with club values. This is the hand here, where partner doesn't have any great desire to penalise but will willingly cooperate if you express interest in sitting for penalties. In this case the double misrepresents your hand and can lead to -280 (or -470 as here). If partner doubles 3C after your 2D reopening, they are at least forewarned and should have better defence than the given hand.
5. A good hand that wants to penalise clubs. Given the vulnerability we will need to take 9 tricks to make up for a game bonus. My offensively oriented hand is going to disappoint partner in this quest, and I would like to send this message. Occasionally I will miss out on +800/1100 and we'll score our normal game contract for a push board.
Weighting each option is complex, but the warning about the offensive nature of the hand is one worth sending. After a 2D bid and 3C rebid, now North can evaluate their hand differently and bid 3D for an 11 IMP swing to the good guys. That's not going to happen every time of course, and sometimes you'll lose IMPs whichever action you take.