>>>Soy sauce, garlic, olive oil, vinegar, pepper and Worcestershire sauce.<<<
You can never go wrong with that mixture.
When I'm marinating thicker cuts like elk backstrap I've started cutting the piece lengthwise and making two long 1" thick steaks (resemble flank) which take the marinade better and cook quickly for med rare. My go-to is a fajita marinade recipe.
I agree with Hank Shaw that prolonged marinating doesn't really penetrate a thick cut any further but just makes the surface extra tender (or mushy).