Bryan Caplan seems to think that the meltdown scenario's effects were accurately estimated: http://econlog.econlib.org/archives/2013/05/conditional_ins.html

Many will look at the Lehman forecasts and confidently declare, "What fools they were." My reaction, though, is bewilderment. How can experts nail the hard question of "What will happen to our investments given housing prices?" yet botch the easy question of "Will unprecedented increases in nominal housing prices continue indefinitely?" I wish I knew.

Mathematicians sound useful for answering the former question, yet no more useful than anyone else for answering the latter question.