They have, although minimal, hardcore influences in their music. For example, take the riffs in and vocal patterns in Violent by Nature
. They have obvious hardcore punk influences. Another example is Convalescence
. Just listen to that main riff, it has nothing to do with Death Metal and the clean vocal patterns come are heavily punk/hardcore/emo influenced (emo here is not intended to be a critic). Though, I have to say many of their songs are pure Melodic Death Metal.