One thing that you can do is order a cab from Washington Flyer. Ask them to pick you up at, for example, the Monaco hotel or Gordon Biersch on 9th. That gives you a fixed time for a pick-up and gets you away from the crowds right around the stadium. The route to the airport is to take 9th south, which takes you right onto 395. 9th is one way there.

Washington Flyer has nice cabs and is reliable. The average DC cab is quite disgusting and I have seen quite a few stranded on the airport access road with the hood open. The fare is the same.

Or if you are comfortable with Uber then set the pick-up point for 9th and F (Gordon Biersch), for example. No idea if the hockey game would cause surge rates; I guess that it's possible. As a rule of thumb an UberX is just above half the price of a cab.