At present, stark differences in Cowboys', Giants' defensive lines

IRVING, Texas -- The Dallas Cowboys rebuilt their offensive line by adding first-rounders Tyron Smith (2011), Travis Frederick (2013) and Zack Martin (2014).

They have been trying to rebuild their defensive line on the fly as well. They took DeMarcus Lawrence, who led the team in sacks in 2015 with eight, and Randy Gregory in the second round of the last two drafts. They made a big commitment to Tyrone Crawford at the start of last season.

But there remains plenty of work to do.

They are visiting with Cedric Thornton on Thursday and he could play the nose- tackle spot Nick Hayden has occupied the last few seasons. They have yet to be linked to any of the remaining pass rushers, but somebody like Andre Branch makes sense.

The Cowboys hold the fourth pick in the draft, and Joey Bosa could be staring them in the face when they pick in the first round next month.

Safe to say a lot of work remains to be done.

As presently constructed, the Cowboys' starting defensive line would look like this for a season opener: David Irving, Crawford, Terrell McClain and Lawrence.

Lawrence is coming back from a discectomy but should be ready for training camp, if not sooner. Crawford is rehabbing from shoulder surgery. McClain played in two games last year before he needed toe surgery that ended his season. Irving was signed off the Kansas City Chiefs' practice squad and while he had some moments, he has work to do.

Gregory will miss the first four games for violating the NFL’s substance-abuse policy.

Now let’s look at the New York Giants' projected starting defensive line: Jason Pierre-Paul, Damon Harrison, Johnathan Hankins and Olivier Vernon.

The Giants won their last two Super Bowls with a stronger than strong defensive front.

Will their free-agent pickups play to the level of their contracts? Vernon had fewer sacks last year than Lawrence. Pierre-Paul is not the same player he was because of the fireworks accident. Harrison and Hankins are solid big bodies, but is Harrison worth the money?

All questions to be answered come this September.

The good news for the Cowboys is they have about six months to keep adding to their defensive line.