They stay good for longer than you want to have them in your freezer, lol.
I like to run hot water from the sink over a bowl with the rat(s) in it. Usually thaws them out in a few minutes. Gotta dry the rat off some but it's usually not a big deal. With any of my balls that are eating normally, never had an issue with them not taking the rat when it's thawed that way.
Also could be that your balls just don't feel like eating. Try sticking the front half of the rat under a heat lamp (if you have one available) for a lil bit and then wiggling it for them. Takes longer but then you'll know for sure the balls just don't feel like eating and it's not the rat 
~jenny
-----
"The python has, and I fib no fibs,
318 pairs of ribs.
In stating this I place reliance
On a seance with one who died for science
This figure is sworn to and attested,
He counted them while being digested."
~Ogden Nash
jenny.thegreenes.org
"If you're happy and you know it,
Bomb Iraq!
If you cannot find Osama,
Bomb Iraq!
If the terrorists are frisky,
Pakistan is looking shifty,
North Korea is too risky,
Bomb Iraq!
