Great work, very interesting to me. Counter to what we're constantly told through the media this stuff can be done. Doing it year after year seems to be the elusive part. Intuitively, once you've proven your technique on 1000+ trades it's not luck.
I developed a fully-automated low-frequency stat arb system that I ran in 2007 based on a perhaps even simpler algorithm. It traded various equities equally to the long and short side regardless of market conditions so widespread rally or collapse was irrelevant. I logged about 20-30 trades/day - much slower.
The results, using no leverage, were +90% in a year with a worst drawdown of 2% and a Sharpe ratio of 2. Total trades were 5000+. Month-to-month the results were very consistent until the uptick rule was nixed in July 2007. August 2007 was a record winner for me, but Sept-Dec 2007 fell flat, not losing, but with greatly diminished profits and the same variation and more frequently getting slammed all-long or all-short instead of a mix that was often near-neutral. Also getting fills better than my orders then completely disappeared, as this was the beginning of the HFT middlemen - including your own brokerage. I shut it down at the start of 2008, keeping the profits intact and moving on to other priorities.
I continued to monitor the theoretical results for a couple of years but the conditions didn't return so I eventually cancelled my data feed.