This is a nice theory, but it only works if the whale can buy more cheap coins than he sells into walls that are not his own. I question whether it is likely that the whale would come out ahead; however, it may explain what we are seeing.
The large majority of the people who speculate are net losers (that's why we have the HODL mantra, since it work so much better for the avg joe than trading).
The more of these cycles of boom and bust on mtGox (since feb 13. - $550 to $300 to $500 to 310 to $540 to $270 to ...) to more money flows from these people to the professional sharks. These people do this for a living. They are very smart and know just the right buttons to push to make the weak tremble and spill because they have been doing it for a long time. And they most probably are colluding aswell.