yep, no algorithm is perfect. We cutted losses seeling at 130US$ last time MtGox was online... 2013 06:50 Buy 0.0042 5 0.0210 BTC
It's not a question of "perfection" (Someone should name an informal logical flaw for people who defend "It isn't working" with "Nothing's perfect")
So if we assume your algorithm is the purple line. Then at what point in the timeline was it generated? On Feb 13th with no additional input? Is it continuously integrating data? At what point was the down turn predicted.
Like so many things, there is nothing about the graph which says that the algorithm is of any use.
(not even touching on that the data has been picked not randomly selected...all the things that tell me that the world needs remedial math)