It's difficult to diagnose and advise based only on a description of "tattered" and "ratty."

Can you post pictures, or a more detailed description?

Thank you for your response. Unfortunately I don't know how to post a picture.

Some of the plants have a majority of blades that are brown- with only a few fresh looking blades. Cutting off the brown blades wouldn't leave much plant behind.

Well, if some of the plants are healthy, and showing fresh growth, you can probably assume the sickly ones should also show new growth, if they are alive.

It's a little late in the season, but you can try shearing them back to eliminate the dead foliage, and see if they rejuvenate before taking them out.

A common cause of failure in Acorus is lack of sufficient moisture. This applies to winter as well as the growing season. A couple of weeks of drought, accompanied by desiccating winds, can do them in.

Thanks again for your response. I don't have the greatest of success with grasses and grass-like plants. I'll try what you suggested.