I often cook frozen chicken or roasts which turn out great. The secret is slow cook using a a meat thermometer and a roaster oven with a temperature dial (not a crock pot with hi-med-low). You only need to plan ahead 8 to 12 hours and from freezer to oven can be as little as 5 minutes.
Chicken should be uniformly heated internally to 180 degrees F and rare roast beef to only 140 degrees F.
Set a roaster oven on around 100 or 120 F for beef or 120 to 150 F for chicken. First rinse the meat, salt and pepper, and place a thin layer of olive oil in the bottom of the roaster oven. Cook for 8-12 hours
A meat thermometer is essential to eliminate over- and under-cooking. Set the cooker temp lower than the desired meat temp because heat builds up in the meat causing the meat to reach a higher internal temperature than what you set on the roaster oven dial.
At these low temperatures the meat both thaws and cooks slowly. The meat will be very succulent and juicy and tasty from cooking slowly in its own juices. I usually cook the chicken breast down because it makes the breast so much juicier. Add potatoes, carrots and onions to the roast beef for a pot roast.
Sometimes I thaw out ground beef in cold water and I would agree with other posters that this type of thawing does seem to affect the quality of the texture and somewhat even the taste. But sometimes you just gotta eat and forgot to thaw something, so wat er ya gonna do?
I cook pasture raised beef and chicken this way. The meat has a different quality than commercial meats, but I think the same general properties apply -- your mileage may vary.