In the case of the May 6th Flash Crash the problem was not primarily due to the market makers but was due to a really large leveraged order coming through at one time.

To use your analogy, it would be similar to a big tubby swimmer doing a canonball from the high board causing all the water in the pool to splash out fast than the market makers could fill the pool.

The tubby swimmer in this case was Waddell & Reed, a money manager that was trying to protect their sizable stock portfolio from dropping (a very valid and legitimate operation).

Link:
http://www.ft.com/cms/s/0/8ee1a816-cd81-11df-9c82-00144feab49a.html

The remedy would be to require the tubby swimmer to learn how to use the pool with others (i.e regulation) and have the owners make improvements in the pool setup (i.e market reform)