I've got 2 month / 30 min period stats from bitcoincharts for bitcoin/usd price. Then I've wrote a soft that calculates ema based on this data, essentially emulating trading bot. Using your strategy with 10/21 this what I've got:
Starting price for btc was $925. I've started with 1 btc or 925 usd for simplicity.
There were 128 virtual trades made, when ema lines where crossing. After that I've ended up with 1.2085 btc == $731, when last price for btc was $605.
Kind of disappointing result. One could just take $925, buy btc for $605 and get 1.53 btc. So, what's the point?
If I read this correctly, you lost 21% (fiat) across 2 months while price dropped 34%. Two comments on this:
1) It sounds like you are choosing a very aggressive timeframe for analysis. This is a trend following system - that means that it loses during periods of market inactivity. Trading on such a short timeframe will expose you to a lot of choppy action. I suggest re-running your studies on longer timeframes. For example, I trade the daily crossover. Over the last two months, there have been only a handful of trading signals.
2) As to your comment about disappointment in trading vs. buy and hold, here is a post from last year:
Profits are in dollars. I'm a trader, I'm only after the kind of profits that I can grow in other markets.
As mentioned, no matter what system you use in a market which tends to increase on average, buy and hold will nearly always outperform. The buy and hold people are sitting at +2000% vs. the +1700% of the system. The difference is that the system has actually banked these profits whereas if BTC were to collapse, the buy and hold investors would...hold.
This has been the recurring debate throughout the year and a half that this thread has been in existence: buy and hold vs. active trading. To restate my previous post:
It really boils down to your philosophy of the markets: are you an investor or trader? Investors believe in a concept and invest in that concept (buy and hold). Traders are after profit while maintaining the ability to live and fight another day (systematic/discretionary trading).