[awm]

Regardless of your criteria, are you looking at some of these hands:

♠JT98 ♥KQT98 ♦98 ♣AQ

This is a crazy double. You have four tricks at best (two clubs, heart, spade). I don't think any human player would make a penalty double on this hand over 2♦-2♠. And sure enough, GIB's double was a huge IMP loss when 2♠X made.

♠QJ965 ♥KJT ♦T7 ♣AQJ

This is a pretty obvious double. You have three potential trump tricks, and additional sources of defense in hearts and clubs, and only two diamonds. Perhaps if partner typically preempts on utter trash you might consider a pass, but 3♦?

♠QJ95 ♥KQJ3 ♦AQ ♣QT6

You even admit GIB's failure to double (or at least bid game) here was crazy. Two trump tricks and seventeen points not enough to double? Where are declarer's tricks? Maybe four trumps and the heart ace and the club ace king (giving partner KJxxxx of diams and out) and 2♠ is still one off.

These are the three that seem really obvious to me. I don't think any good player would make the decisions GIB made, and these three decisions lost on the order of 30 imps.

Surely GIB makes mistakes in other auctions as well, but I don't think the frequency of mistakes as responder after 2♦-Pass is going to be all that high because GIB may not even be "out of book" yet on that auction. And it sounds like GIB was not infrequently making crazy calls with the given hand after 2♦-Pass-3♦-Pass-Pass either.