Sports bar in SilverLake Echo Park???
I think your best bet would be either Ye Rustic Inn (on Hillhurst in Los Feliz) or the bar at El Compadre (on Sunset in Echo Park). Both have televisions that are tuned to sports, although you might want to call first to see if the game they will have on is the Yankees/Red Sox. Food-wise, my preference would probably be Ye Rustic, if only for their buffalo chicken wings.
Edited to add: they also have televisions tuned to sports upstairs in the Beer Garden at the Red Lion (on Glendale in Silverlake). They tend toward soccer, but I've watched baseball games there before. If you are in the mood for beer and sausages, this could be a good choice.
Edited again to add: I would bet money that Hollywood Billiards (on Hollywood Blvd. in Hollywood) would have the Yankees game on. They serve pretty standard bar food as well. It opens at 4 -- is that too late?
All those mentioned will do you well, but the Hollywood Billiards I think has joined up or been replaced by a new Cafe Tropical (same as one on Sunset and Parkman). The new place is very near the intersection of Hollywood and Wilton, on the south side of the street, and it's a big purple building. I highly recommend it for sports. Tons of seating, TVs and in the day at least, almost empty. Plus you can get yummy Cuban sandwiches now. Full bar, and very decent Cuban style coffee (not quite as good as the original Tropical location).