PHILADELPHIA (973espn.com) — Bruce Arians knows a thing or two about quarterbacks, so much so that the veteran Arizona Cardinals coach released a book earlier this year titled "The Quarterback Whisperer: How to Build an Elite NFL Quarterback."

A York, Penn. native who used to run things on North Broad Street at Temple in the mid-1980s, Arians has had a hand in the development and stewardship of Peyton Manning, Ben Roethlisberger, Andrew Luck and his current signal caller, Carson Palmer.

So when he talks about the position you better be listening and Arians is pretty impressed with what he sees from the Eagles' Carson Wentz after 20 NFL starts.

"I loved him coming out," Arians said during a conference call with the Philadelphia-area media on Wednesday in advance of Sunday's game between Arizona and Philadelphia. "He really reminded me a lot of Andrew Luck. He's big, strong, physical, and played in a [pro-style] offense [at North Dakota State]. He has that linebacker-mentality playing quarterback, it shows up in his toughness. He can really hurt you, out of the pocket and in the pocket."

Like a lot of observers, along with Luck Arians also brought up his old student in Pittsburgh (Roethlisberger) to describe what Wentz is capable of doing when it comes to extending plays with his size, strength and athleticism.

"He's such a good athlete, he reminds me of Ben in a lot of ways," Arians said, "how he just throws guys off of him in the pocket and makes big plays downfield."

Wentz has shown the expected improvement in his second season to date, throwing for 1,058 yards with six touchdowns versus two interceptions during the Eagles' 3-1 start.

On Tuesday, Eagles offensive coordinator Frank Reich, lauded Wentz's strides when it comes to situational football.

"Really what sets you apart as a quarterback, is how you perform in situational football," Reich said. "That's third down and red zone. Then what kind of a knack do you have of making big plays on first and second down? That's really what separates those elite players. And so becoming a playmaker on third down and in the red zone is a big part of any quarterback's development. I think [Wentz] takes a lot of pride in that. I think he knows that. I think he studies it a lot."

Arians added one more category to that equation:

"Can you bring your team back from adversity and win games?" the Cards coach asked rhetorically. "I think that's what separated Andrew Luck as a rookie. I think he still holds the record as a rookie with fourth-quarter comeback wins. I think you see that in Carson, that he can bring his team back."

JERNIGAN MISSES PRACTICE

Defensive backs Jaylen Watkins and Corey Graham were able to return to practice at the NovaCare Complex on Wednesday but Fletcher Cox remained out with a calf strain and was joined on the sideline by his lieutenant on the interior of the Eagles' defensive line, Tim Jernigan.

Jernigan sat out with a heel contusion although coach Doug Pederson said that the Florida State product is not in danger of missing Sunday's game against Arizona. The good news at DT is that Destiny Vaeao returned to practice after missing the past three games with a wrist injury.

Pederson also offered updates on the team's two injured cornerbacks: Ronald Darby and Sidney Jones.

Darby, who dislocated his ankle in the season opener against Washington, was originally estimated to be out for four to six weeks. With a short week after Sunday's game against the Cards, the best-case scenario for Darby would seem to be Oct. 23 when Washington visits Lincoln Financial Field for "Monday Night Football."

"We will continue with the rehab this week and get him moving a little bit more," Pederson explained. "He is on schedule. But, with the severity of the injury, it is going to take time. I'm not going to hold it in a box. Things take time. You saw the replay, you saw the ankle. It takes time."

As for Jones, who remains on the NFI list after tearing his Achilles' during Washington's Pro Day in March, the rookie would be eligible to start practicing after the Carolina game on Oct. 12 and the Eagles would then get three weeks to decide whether to put him on the 53-man roster or move him to injured reserve.

All Pederson would say is that Jones is progressing.

"As I have said all along, there is really no timetable for him," the coach said. "We want to make sure is 100 percent. You look down the road, and there is not only the health issue, but getting into football shape too. I'm not going to stand here and give you a timetable."

PRACTICE SQUAD TWEAKS

Cleveland signed Bryce Treggs to its 53-man roster on Tuesday and the Eagles have added two players over the past two days, cornerback D.J. Killings and receiver/returner Rashard Davis.

Killings was among four players the Eagles worked out last week (OT Givens Price, DB Damian Swann and OC Anthony Fabiano were the others). He is a Central Florida product who originally signed with New England as an undrafted free agent back in May.

Davis, an undersized 5-foot-9, 180-pound WR out of James Madison, was with the Eagles for part of training camp and Dave Fipp lauded him for his return ability.

-John McMullen covers the Eagles and the NFL for 973espn.com. You can reach him at jmcmullen44@gmail.com or on Twitter @JFMcMullen