Posted 2012-January-24, 02:46
I ran 1000 deals through Dealmaster Pro with this hand and opposite a 15 HCP balanced hand, 3NT only made 33%. Opposite a 16 HCP hand, the percentage for 3NT went up to 54%. It seems that this is only worth an invitation to 3NT.
If you're thinking that 3NT might make more often without double dummy defense, I ran 1000 deals with a random 3=3=4=3 distribution, 9 HCP, opposite a 15 HCP balanced hand and this made 36%. This is certainly in line with conventional wisdom to invite with 9 HCP and bid game with 10 HCP. It's a somewhat surprising result since all these jacks and 10's don't make this suitable for an upgrade, even less so than a random 9 HCP.
After the fact reasoning: KQJ tight isn't that great unless partner has ace or 10 fourth, and is bad duplication opposite ace doubleton or tripleton. What plays better,
Axx opposite J102
or AJ10 opposite xxx, or maybe AJx opposite 10xx. True, this may not happen that often, but certainly more often than if J102 is a given.
Another possibility is that jacks aren't worth a full 1 HCP but that's a can of worms I don't want to get into.