When faulting the Raiders for squandering five second-half leads this season or failing to blow out any teams, perhaps it bears taking into account what coach Dennis Allen has at his disposal.

Take the Dallas Cowboys game, for example, in which the Raiders started Matt McGloin at quarterback, Jeron Mastrud at tight end, Andre Holmes and Rod Streater at wide receiver and Marcel Reece at fullback.

The common denominator? All entered the NFL as undrafted free agents. Then there’s running back Rashad Jennings, a seventh-round draft pick.

That doesn’t even factor in the defense. The point is, it should pass as more surprising that the Raiders have been competitive in all but two games so far and not that they won only four of their first 12 games.

It also bodes well that general manager Reggie McKenzie and his scouting department have the eye to spot players such as McGloin and Streater, as they did each of the past two seasons, as a means of bolstering the roster.

Injuries and subpar play by players counted upon to play starring roles, in part, helped thrust Streater and McGloin into starting roles. Their desire, work ethic and overlooked talent enabled them to succeed once given an opportunity.

“When you don’t get drafted, that kind of puts you back,” Streater said. “But it also gets you that edge. You want to work hard and you always feel like you got something to prove.”

Streater and McGloin made immediate impacts once they received starting gigs. For Holmes, it took until the Cowboys game for him to take what he has done for months on the practice field and exhibition games into a regular-season game. And this is his third season.

He was with the Cowboys last season and also spent time with the Minnesota Vikings and New England Patriots. Holmes said

“It’s taken me three years to be able to do it and it’s just the development and me figuring out the skills that I need when I’m out on the field,” Holmes said. “Part of it could be opportunity and things like that, but I mean, I wouldn’t say that I wasn’t doing it before or anything like that. It was just the right time.”

Holmes sat out the first four games while serving a league suspension. He spent the next seven games either on the inactive list, on the sideline as a backup or getting a few reps here and there.

Inconsistent play by rookie Brice Butler, second-year receiver Juron Criner — he’s now on season-ending injured reserve — and Jacoby Ford, along with an injury to regular starter Denarius Moore, created the opportunity for Holmes to shine.

Streater said he and others aren’t surprised to see Holmes enjoy a breakout game. Holmes caught seven passes for 136 yards against the Cowboys, or more than he produced in his career to that point.

“He’s been doing this way back since camp,” Streater said. “The four-game suspension kind of threw him off, but you see he goes out there and makes plays. He might not be the fastest but if you put the ball in his area, he’s going to come down with it. He’s very impressive.”

And it’s just as impressive that the Raiders now have a few receivers to carry over into next season and beyond. Ford is in the final year of his contract, and he’s unlikely to be offered a new contract. Criner isn’t a sure bet to be asked back, either, even though he’s still under contract.

— Jennings wasn’t permitted to speak with the media Monday, even though he was in the locker room, because he’s still suffering the effects from a concussion. That’s in keeping with the league rules for players going through the league concussion protocol.

For what it’s worth, Jennings was smiling and playing around with his teammates, which bodes well for a quick return.