mrdct, on 2011-March-10, 16:19, said:
Yeah, maybe after trick 1 I'd be asking for their card. But "if it was something systemically alertable, they would have Alerted" - and after seeing their card where 2NT was, in fact, 20-21, now I'm having to ask "so, does he play any other system with someone else with a conventional 2NT opener? What is it then?" And now we are in serious UI territory.
I definitely would, in England, at least, assume that he bid 2NT 12-14 - but now, at least, he would probably have realized when partner didn't announce the range. But if this is a pair that 19 months in, still occasionally forget to announce...(it's been almost 20 years here, and people still forget to announce 15-17).
Now, if it *had* been a misbid - say South plays this "good 3m preempt" with someone else, and forgot - then "no harm, no foul". But North forgot the bid (and didn't Alert), South failed to correct the "explanation" - I think they deserve what they get.
At BAM or MP, trading -500 for a 50+% better score, 49% same score, <1% -1640 is insane - how much topper can it get? At IMP-scored teams, the difference between 500 and 800 could win the match, and I might lay 100-1 odds, even if I won't lay 12-1.