Vacuum sealed frozen salmon burgers - seal broken due to thawing?
The question I would have is whether it was frozen when you bought it, or if you froze it yourself. If you froze it and the packaging was good when you did then there's no reason to throw it out unless it's gotten too freezer-burned to be palatable. It's the temperature of the freezer, not the packaging that preserves food when in the freezer, so it should be safe providing it was properly handled before being frozen. 
As for the bag being loose it may very well have a hole in it, it's more likely to have happened in the freezer than during thawing. Because you froze it yourself and the packaging was good you know whatever happened occurred after you bought it, so it should be just fine. 

If you bought it frozen then I would suggest throwing it out because you don't know when the packaging was broken or what the food could have been exposed to.