Steelers DE Cameron Heyward is out for the season with a pectoral injury

Defensive end Cameron Heyward, one of the leaders of a Pittsburgh Steelers defense that has been struggling this year, will miss the rest of the season with a pectoral injury.

Heyward announced the news on his Instagram account Tuesday after suffering the injury in Sunday's loss to the Cowboys and then reportedly undergoing two evaluations.

The 4-5 Steelers rank 25th in the league in yards allowed per game, and have lost four straight. Heyward has three sacks this season after posting seven last year and 7.5 in 2014. He was the 31st overall pick in the 2011 draft and has been a starter since the 2013 season.