[uva72uva72]

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The GIB 2/1 convention card specifies "light" pre-empts. Take a look at this "light" 3♦ opening: 2.5 quick tricks, 7-4 shape. Those who follow the rule of 20 (I know the BBO robots do not) would open this 1♦; even for those who use the rule of 20 only for the purpose of deciding whether to pre-empt or not the 21 points (10 HCP plus 11 for length in two longest suits) this would be a definite "not." Then there is the fact that the side suit is a major, and that the hand also contains a ♠ void, both of which (and in combination) argue strongly against pre-empting.

Notice, too, that the BBO cognoscenti all bid 3NT, knowing that such contracts make 99% of the time, even if the ♥stopper is Jx opposite x. Here, West miraculously underleads his ♥ honor (something a robot rarely does unless it is to underlead AQ into the strong hand against 6NT or 7NT), but East, after cashing AK, switches to ♠ because it knows East is more likely to have lead low from xxx than from the Q. The upshot is that those (not including me) who reached the most reasonable contract(5♦) got a below average score. This is an area (opening leads, and the impact they have on the bidding) in which BBO, to its detriment, most diverges from the experience of playing bridge against humans.

[Bbradley62]

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GIB absolutely requires 11HCP to open at the 1 level. GIB means "potentially light pre-empts", not "specifically light pre-empts". And, "light" is the middle of the three choices -- it's not "very light".

[steve2005]

Why doesn't east Gib continue ♥. Is this like not leading Ace against 7N? because it might get the tricks it's entitled to.

[1eyedjack]

If I am confident that west has only 4 Hearts, and particularly as West often will not lead strongest suit, then as East I might well switch to spades, but would do so before cashing heart ace.

[johnu]

Opposite a "light" 3♦, why would you expect to take 11 tricks?