Yeah, frozen meat will kill your burger.
If you don't grind your own beef, you should at the very least use fresh, never frozen meat. Freezing meat causes the water inside the cells of the beef to expand, bursting the cell walls and damaging the meat. In addition to creating a noticeable difference in texture (your previously frozen beef will be mushy most likely), once the meat is thawed the water will leak out rather easily since the structural integrity has been burst.
If you run a dedicated burger place, I would recommend that you invest in a commercial grinder and decide on a blend of beef cuts you would combine to make a burger grind. A mixture of chuck, brisket (untrimmed), short rib, and sirloin would be a good start. Any or all of the above, with varying amounts depending on what you find you like.
Other than cleaning, using a commercial grinder is a cinch, relatively quick, and would result in a vastly superior product for you.
If you aren't using frozen beef, then it must be something in your technique or your ingredients. Are you over cooking them? Seems obvious...but I had to ask.