Why does my roast beef smell wonderful but tastes bland? My crockpot roast beef has the best aroma ever but the flavor of the finished product is only average. I had a 4 pound tri-tip roast and seasoned it with the usual onion, garlic, worcestershire sauce, cumin, basil, beef gravy packet, and enough beef broth to just cover roast in the crockpot. We walked in the door and the delicious aroma filled the whole house. But, when eating the roast, it was just okay. Lots of delicious aroma but very little flavor in the roast beef.

Why is this?
If we're talking about a solid, four pound cut of beef - the only flavor you're ever really going to get is on the exterior and just a little bit into the interior of the meat.  

That said, cooking in the spices/components you list still may provide liquid gold.  I would simply take some of the liquid that's leftover in the slow cooker after the roast has cooked and make a gravy out of it.  You'll get the flavors you put in and have something to sauce the interior of the meat - that have been flavored with the juices of the meat as well. 

Otherwise, if you're looking to 'infuse' more flavor into the beef itself, you'll need to consider something like a stew rather than a whole cut.