They were aggressively getting funds and building ethanol facilities at that time with no revenue to show for several quarters. It takes time to construct, so people lose patient in the stock.
Now their facilities are starting to make tons of money for them, so people can see their hyper-growth revenue and earning power, so the stock is going up very fast.
Get in and buy GPRE while it is still dirt cheap. Insiders and smart investors are the ones loading up the stock aggressively now with no analyst coverage. By the time the analysts find out about GPRE, we would be laughing all the way to the bank already.