IRVING, Texas >> Linebacker Rolando McClain was suspended 10 games today for his second violation of the NFL’s substance-abuse policy in as many years, leaving the Dallas defense with three banned starters to open the season.

McClain, who was suspended the first four games last year, is now sidelined along with defensive end DeMarcus Lawrence, who was suspended four games on a substance-abuse violation after an appeal was denied.

The other suspended player projected to start is pass rusher Randy Gregory, who also will be out four games on a substance-abuse ban. The former Nebraska standout slid to the Cowboys in the second round of last year’s draft after testing positive for marijuana at the NFL combine.

All three will be allowed to participate in training camp, which starts July 30 in Oxnard, California, and in preseason games.

Dallas has had four defenders with season-opening suspensions over NFL policies the past two seasons. Former defensive end Greg Hardy had a four-game ban last year under personal-conduct guidelines related to his domestic violence case in North Carolina.

McClain, who turns 27 Monday, came to Dallas in a trade before training camp in 2014 after Sean Lee sustained a season-ending knee injury during the offseason. He resurrected his career with two solid seasons after flaming out early in Oakland, which drafted him eighth overall in 2010.

After sitting out the 2013 season and twice walking away from football while in Baltimore, McClain filled a glaring need and finished second in tackles to safety Barry Church two years ago as the Cowboys won the NFC East and their first playoff game since 2009.

But McClain’s work habits were always a question, and he missed all the voluntary workouts in both offseasons in Dallas. He reported for mandatory minicamp both years, but wasn’t available to reporters this June.

If Dallas prefers to keep Lee in his most natural spot at weakside linebacker, Anthony Hitchens is likely the first choice to replace McClain in the middle. Hitchens was a fourth-round pick in 2014.

The Cowboys had just released franchise sacks leader DeMarcus Ware when they moved up in the second round to get Lawrence in 2014, believing he was the last pass rusher available with a chance to have an immediate impact.

Lawrence missed half his rookie season after breaking his right foot in training camp, but showed promise late. The former Boise State player had a team-leading eight sacks in his second season last year.

Gregory was limited by an ankle injury early in his rookie year and finished without a sack.

Figuring out the pass rush will be a high priority at training camp for the Cowboys. Benson Mayowa, signed to an offer sheet that Oakland didn’t match, had arthroscopic surgery on his left knee in June and may not be ready when camp opens.

Even counting Lawrence and Gregory, none of the 10 potential end rushers on the Dallas roster has 10 career sacks. Lawrence and Tyrone Crawford lead with eight apiece, although Crawford has been more effective at defensive tackle and is expected to play there.