What do baseball and trading system drawdowns have in common? A lot more than I ever realized.
If you haven’t read the book or seen the movie Moneyball (which I highly recommend), professional baseball adopted a statistical approach to recruitment and gameplay around 2000.
The Oakland Athletics adopted the approach before any team. They experienced tremendous success in their first system-driven season, despite countless expert predictions of imminent failure.
I started reading The Signal and the Noise by Nate Silver last night. The baseball chapter picks up where Moneyball left off. Dustin Pedroia, a star second baseman for the Boston Red Sox, enters the scene as an unlikely success story.
Most scouts overlooked him. He is short. He has a paunch and bowed legs. Nobody looks at the guy and thinks “professional athlete”.
Sticking with the system
Pedroia batted a lackluster .198 when the Red Sox brought him to the major leagues in August of 2006. The first month of the 2007 season started off even worse at .172.
A team like the Cubs, who until recently were notorious for their haphazard decision-making process, might have cut Pedroia at this point. For many clubs, every action is met by an equal and opposite overreaction. The Red Sox, 一方、, are disciplined by their more systematic approach. And when the Red Sox looked at Pedroia at that point in the season, James told me, they actually saw a lot to like. Pedroia was making plenty of contact with the baseball – it just hadn’t been falling for hits. The numbers, most likely, would start to trend his way.
“We all have moments of losing confidence in the data,” James told me. “You probably know this, but if you look back at the previous year, when Dustin hit .180 or something, if you go back and look at his swing-and-miss percentage, it was maybe about 8 パーセント, maybe 9 パーセント. It was the same during that period in the spring when he was struggling. It was always logically apparent – when you swing as hard as he does, there’s no way in the world that you make that much contact and keep hitting .180.”1
Trading System Drawdown
Every trader goes through a slump – even the best of them. When your trading system drawdown reaches uncomfortable levels, how do you cope?
I had the opportunity to lead managed fund sales at one of the largest forex brokerages in the world. The product was the Sentiment Fund and it was AWESOME. When the fund took off and upper management suddenly got involved, the fund had $40 million under management and nearly 1,000 investors.
If there’s one thing that you can count on with forex traders, it’s that they are going to lose. All the time. No doubt about it.
The firm received real time information on the positions of all clients. Whenever too many traders held positions long or short, the fund did the exact opposite.
それはそれ. 、 automated strategy was stupid simple, but the returns were amazing. The aggressive fund kept the leverage at 2:1, yet was on track to earn 40% 毎年.
Two months before the hand off, the fund experienced a sharp drawdown of -8%. Like most people, investors thought of 40% returns as 40/12 = 3.3% profit per month. They don’t think about the natural slumps that happen – just like the one Pedroia experienced.
こと “surprise” drawdown caused a mass herding effect. It didn’t matter that the fundamentals of the strategy were unchanged. Forex traders didn’t wake up smart last month and know how to game the system. Bad luck happens to the best strategies. それにもかかわらず, investors ran for the exits from a world class strategy.
Were the guys on the systems desk worried about the strategy that they built? No way! When Pedroia went through his slump, he could have overreacted and start messing with his batting stance. He could have adjusted his distance to the plate or any number of things.
Pedroia knew that his system was good. The systems guys knew their strategy was phenomenal. In spite of all the pressure, they held firm and blew past the drawdown by the time I handed off the sales effort.
What element of trading matches the “swing-and-miss percentage”? The Red Sox clearly used it to justify sticking with their system. In Sentiment Fund’s case, it was knowledge of the underlying system.
How can quantitative traders with less obvious fundamental theories know that their system is sound? I’d love to hear your comments.
1. Excerpted from The Signal and the Noise by Nate Silver, ページ 104.