Simple thing: The Salem is considered to be the best destroyer in FAF against a whole variety of units. It can walk on land, it is really good against subs, it's AA is good, it has long range and it is hard to dodge.
I think it is too good at killing ACUs. When you are dodging, you cannot outrun them because they can follow onto land and dodging slows you down so much. I do not think a mobile unit with such a long range should be that hard to dodge.