How can I improve this recipe for French Dips in the Crock Pot?

Today I made a recipe for French dips with the beef cooked in the crock pot. The recipe called for a rump roast (fat trimmed), 1 can beef broth, 1 can condensed French onion soup, and 1 beer, all thrown into the crock pot and cooked on low for 7 hours. The meat was cooked but it was tough. It didn't fall apart like I expected. The au jus was bland. It didn't have that strong onion flavor. What went wrong, and what can I do to improve this recipe?