I would have thought there are a multitude of ways in which a small a/c could bring down a bigger one, however well built, and sustain relatively "minor" damage itself. Apart from the obvious immediate failures that may occur to important bits like control surfaces from a glancing blow at cruising speed we don't know what might have happened to the bits of wing which separated from the Embraer. Were they ingested by one of the B737 engines? Etc etc etc.
I'm assuming this accident was caused by a mid-air, which it seems is not yet clear.
Anyone know if there was any comms with the Boeing after the problem occurred?