Harvin (hamstring) has been ruled out ahead of Sunday's game against Houston, Teresa Varley of the Steelers' official site reports.
Harvin suffered a hamstring injury during Pittsburgh's Week 3 win over Las Vegas, and it seems as if the injury is more severe than the team originally thought. As of now, the Steelers don't have another punter on their roster, so it's currently unknown who will assume the punting duties this coming Sunday.