Derek Carr, behind full O-line, puts on show in Raiders' 24-20 loss at Cowboys

The Oakland Raiders played their starters for most of the first half Saturday night -- EJ Manuel replaced Derek Carr with less than two minutes before halftime and Connor Cook had the Raiders inside the 10-yard line with less than 10 seconds to play. But Cook could not connect on a pair of fade passes, the latter as time expired, and the Raiders fell to the Dallas Cowboys 24-20 to remain winless in the preseason at 0-3. Again, the Raiders' offense was efficient and explosive while Oakland’s defense was exposed and exploited ... at times.

QB depth chart: Carr again showed patience and poise in the pocket, even if he seemed to use flips of his wrist more than his legs when throwing the ball downfield. Call it touch, then. And accuracy. Carr finished 13-of-17 for 144 yards and two touchdowns, a 17-yard bullet to Cordarrelle Patterson and a 48-yard laser on a pump fake to Amari Cooper. In two preseason games, Carr is a combined 20-of-26 for 244 yards with four touchdowns and a passer rating of 128.9. Yeah, Carr is ready.

When it was starters vs. starters, the Raiders looked …: Offensively, the Raiders again looked sharp and ready to be put in bubble wrap until the season opener at the Tennessee Titans on Sept. 10. Defensively? Well, let’s just say, again, if this defense continues to get picked apart like this, the Raiders are going to have to win a lot of shootouts. Or, as Matt Millen said on the team broadcast, “The offense is good enough to take them a long way [but] the defense is what’s going to hold them back. ... I hate to say this, but they’re going to have to find a middle ‘backer some place. Maybe on the waiver wire or make a trade.” Paging Perry Riley Jr.?

One reason to be concerned: Penalties, as in 12 for 132 yards. Among those flags, Oakland had three personal fouls, including two on one Dallas scoring drive. Last season, the Raiders led the NFL with 146 penalties, including an NFL-record 23 penalties in an overtime win at the Tampa Bay Buccaneers.

That guy could start: Jelani Jenkins was signed to be the team’s weakside linebacker, and after an uneven offseason program, and with Cory James sitting out Saturday, Jenkins finally got a chance to show his wares as a starter. Jenkins was credited with four tackles, three solo, on the Cowboys’ opening drive, including one stop for a loss.

Rookie watch: You can’t say undrafted linebacker LaTroy Lewis did not make an impression this preseason. Especially not after his athletic and acrobatic 65-yard fumble recovery out of the air for a touchdown against the Cowboys. The play came when a blitzing Antonio Hamilton hit Cooper Rush as he attempted to pass, the ball popping straight up and into the arms of an onrushing Lewis, who also has two sacks this preseason.

Two key players injured: Cornerback David Amerson left the game in the first half after taking a blow to the head making a hit; he went directly to the locker room after staying prone on the field for a bit. Later, fullback Jamize Olawale pulled up after a long run that was negated by penalty, Olawale hitting at his left quad as if he suffered a cramp on the top of his leg.

Thin at cornerback: Amerson was replaced by Dexter McDonald on the outside, and Sean Smith also saw reps with TJ Carrie getting the start at right cornerback. But in the third quarter, McDonald suffered an undisclosed injury and, after being examined by trainers on the field, he, too, left the game. As one Twitter follower suggested, Darrelle Revis is available. Then again, so is Nnamdi Asomugha, for what it’s worth.

Making their debuts: Left tackle Donald Penn, who ended his 26-day holdout this week, joined the first-team offense on its second series, as Marshall Newhouse moved back to right tackle. Jihad Ward got into the game in the second half and had a penalty with a hands-to-the-quarterback’s-face. And second-rounder Obi Melifonwu played throughout, debuting with the first-team defense -- Dallas threw right at the safety -- and was still playing late in the fourth quarter.