If you have an EA that's showing a 50DD in the last year, I'd say walk away from it. But it it was ancient history, you need to realize that. If you have traded forex for any real period of time you'll know that the currency pairs often go through correlations that fluctuate. For example, at times gbp/usd trades in tandem with eur/usd. While other times the two are not correlated at all. Why does this happen? For a lot of reasons, but one reason is that the same economic conditions that exist in Great Britain, exist in europe as a whole. In other times Britain fairs far better than Europe. So their currencies don't behave the same way. Currencies go through changes. And keep in mind that a currency pair that's trading at 1.0000 behaves far differently than when its trading at 2.0000. Their Daily ATR change too. If you're new, that's Actual True Range on a Daily basis. Instead of trading 50 pips a day, they trade 100 or more.
You need to know that when you're evaluating an EA. It's not going to behave now the way it behaved years ago. And that can be taken both ways. If an EA succeeded 8 years ago, don't count on it working now. I am not saying, it CAN'T. I'm saying don't expect it to. Look at the recent past. Give more weight to recent performance.