OXNARD, Calif. -- It's not too difficult to construct a case for a Dallas Cowboys regression in 2017. Whether it's a potential sophomore slump for quarterback sensation Dak Prescott, or more injuries for Pro Bowl receiver Dez Bryant, or a possible suspension for powerful running back Ezekiel Elliott or the reality few teams win 13 games in consecutive years in this league of parity, options abound as to why this team might slip this season.

And in the fact the Cowboys face a tougher schedule and play in an NFC East that might be as competitive as any division in football for a change, and consider the doctrine that a half-dozen playoff teams or so generally lose their way the following season in the NFL and -- well, let's just say you've got my attention.

For all of those potential pitfalls, I'd suggest an additional factor that could ultimately be the Cowboys' downfall beyond all of the others: This roster remains utterly devoid of proven pass-rushing talent.

Defensive coordinator Rod Marinelli is a maestro and a master schemer, and few can do less with more, but having him take this group of tackles, ends and linebackers into the season may be requiring feats of magical to rival anything David Blaine has ever orchestrated. Randy Gregory, a top pick selected to infuse sacks into the lineup two years ago, remains suspended. First-round pick Taco Chartlon is having a rocky transition to the pro game based on early returns.

And as much as Prescott and Bryant and Elliott -- the new triplets of this offense -- get talked about, few players on this roster are more important than defensive end DeMarcus Lawrence, far and away the club's most talented edge force and someone who may have to post double-digit sack totals if the Cowboys are going to reach the playoffs for consecutive seasons for just the third time in the last 20-plus years.

If you are looking for a candidate for a breakthough year in terms of quarterback pressures among this unheralded bunch, Lawrence (6-foot-3, 225 pounds) is the guy. Ask around training camp who here can get to the passer, and his hand will shoot up as he runs to the head of the class. It's a prophecy the Cowboys desperately need to come true.

"I wouldn't be holding my hand up in the back of room," Lawrence, 23, told me after a spirited practice at the team's training camp facility here. "I'm going to stand up and walk to the front of the room and let everybody know that I'm going to be accountable, and make sure I take care of my body and get the job done, not just for myself but for my teammates also."

Lawrence, enters his fourth season -- a contract year for him -- with much to gain or lose. He burst forth with eight sacks in 2015, but, like so many in the team's defensive line room in recent years, fell prey to off-field issues. He was suspended for four games in 2016 for violating the league's substance abuse policy and was a non-factor the rest of the season, trying to play through a painful back injury that sapped his effectiveness (he ended up with just one sack in the lost season for him).

In the meantime, Dallas' bend-but-don't break defense lost ample talent to free agency, added nothing of note to the defensive end situation save for drafting Charlton, and this after the team posted a pedestrian 36 sacks last season, 13th in the NFL. By Cowboys' standards it was a major step forward -- they finished 31st and 28th in total sacks the two previous seasons -- but the pass rush will have to significantly improve if this team is to be a postseason factor.

No Cowboy had more than six sacks -- only two teams had a lower figure from their team leader (Cleveland and Pittsburgh) -- and the Cowboys haven't had anyone hit 10 sacks or more since 2013. There is not one Cowboys player on this 90-man roster who has notched even 15 career NFL sacks, and they've already lost defensive end Tyrone Crawford, whose modest 12.5 career sacks in 61 games is tops among any end on the Dallas roster, indefinitely to an ankle injury (team officials believe he'll be back for Week 1).

The six defensive ends atop the depth chart -- three on the left and three on the right -- have amassed a grand total of 39.5 sacks in 175 combined NFL games. On the bright side, coaches here were impressed with the Cowboys' ability to get timely sacks late in games using only a three-man rush, but are eager for more pressure overall. Imposing on paper, this lot is not.

So consider me among those who still cast a skeptical eye that the Cowboys will be able to duplicate the 11-game win streak they rode last season, particularly if the offense is not as dominant as a year ago with defenses now having a book on Prescott and Tony Romo no longer waiting on the sidelines as a security blanket at the quarterback position.

The Cowboys desperately need a breakout season from Lawrence. USATSI

"Yeah, I think it's fair you could say the offense carried us last year," Lawrence said after taking a pensive pause to consider my assertion. "But it's a team sport and you've got three phases of football -- offense, defense and special teams -- and you need to win two of those three to win a game. And sometimes we didn't come correct in the games, and sometimes the offense didn't. We're not going to point fingers. We've got special people on offense and special people on defense."

That's debatable. There are few entrenched, familiar faces on this Dallas defense still here, and one of them, glue linebacker Sean Lee, left practice early with a hamstring issue Thursday (injuries have been unkind to him throughout his career). So keeping Lawrence's back as healthy as possible is paramount

"So far DeMarcus is working hard, and he's on track to getting back to his form he was in a couple of years ago, if not better," said assistant defensive line coach Leon Lett, a legendary Cowboy linemen in his playing days. "That's what we're working on, to get back to two years ago. I think he's on track, it's just a matter of timing with the defense and getting quality reps. He has all the tools to be an excellent player."

As to the pass-rushing resumes of the other Cowboys atop the team's depth chart along the front seven, well, have a look for yourself (from top to bottom on depth chart at each position):

Left Defensive End

Defensive Tackle

Right Defensive End

Strong Side Linebacker

Middle Linebacker

Weak Side Linebacker

Things look bleak, but there are some other potential bright spots. Collins very quietly made big strides last season and emerged as someone the team believes can continue to grow. He wasn't satisfied with last year's output by a long shot.

"It's our job to get sacks and that's what we've got to do," Collins told me. "Where did we finish last year? ... 13th? That's not good enough."

As for Collins' personal ambitions, "I'm only responsible for myself and I'm going to shoot for the highest goal," he said. "The best I've seen do it (pass rush from a defensive tackle spot) was Warren Sapp. He set the standard and he had 16.5, so why not shoot to be the best?"

Should he accomplish even half that lofty mark, Collins might end up leading this team in sacks. There is a bit of buzz about undrafted rookie end Lewis Neal, who could make the team if he keeps up this output in preseason games, but the tepid first few weeks for Charlton, taken 28th overall out of Michigan, bears close monitoring as well.

There is hardly an overabundance of options. Lawrence clearly is the brightest of the bunch. This defense may go as he goes, and this season may go as the defense goes, and the need for more bodies around the opposing quarterback is lost on no one in this training camp.

"Obviously, always has to get better," coach Jason Garrett said this week. "It's been a point of emphasis for us. We've had some different guys in the mix. Some guys have been in and out of the lineup, but again a really good opportunity for young guys to show what they can do, both in practice and in preseason games."