PHILADELPHIA (973espn.com) - The third preseason game is often referred to as a dress rehearsal and that description reaches far beyond the 60 minutes of football you will see in Cleveland on Thursday night.

It also describes the lead-up to the contest where a coaching staff will try to clone its regular-season routine in an effort to create a trial-run.

Much has been made of the Eagles' nickel-back competition for a number of reasons, not the least of which being it's one of the few jobs up for grabs on the Super Bowl champions as training camp.

The first two preseason games were spent evaluating Sidney Jones, Avonte Maddox, De'Vante Bausby and even D.J. Killings in an effort to find the path forward to replacing Patrick Robinson, who made the transformation from nearly being cut in August of last year to the best slot cornerback in the NFL when the Eagles raised the Lombardi Trophy in Minneapolis back in February.

On Tuesday, secondary coach Cory Undlin telegraphed the decision by beginning individual drills by working on combination coverages and it was Jones, the one-time star at the University of Washington who essentially redshirted his rookie season while rehabbing a torn Achilles suffered at his pro day, working with the starters: Jalen Mills and Ronald Darby at corner and Malcolm Jenkins and Rodney McLeod at safety.

And remember, everything this week is mirroring what the Eagles want to do while preparing for Week 1.

Jones never played in the slot at Washington and doesn't fit the profile for the position from a length and physicality standpoint but when you don't have the perfect fit available, the default setting for most defensive coordinators is to get the most talented people on the field and let the chips fall where they may.

"Just like everything, we're still a work in progress," defensive coordinator Jim Schwartz said when discussing the position earlier this week. "Nothing has been settled there."

Perhaps, but it would take an awful big flub at the dress rehearsal for Jones to lose the spot to Maddox, the rookie fourth-round pick who may ultimately end up at the position by 2019, or Bausby, a long, speedy corner best-suited for outside work.

"Each guy brings a little bit different skill set, little bit different strengths and weaknesses, to the position," Schwartz explained. "I think the competition is good. This game is going to go a long way to deciding who is going to be out there in the opener."

If you can find a prop bet put your money on Jones but if you want the longshot, use the field because the only other options for Sept. 6 involve moving parts. In other words, sliding Mills or even Darby inside when the nickel is on the field and having Jones rotate in as an outside CB or the old fail-safe of lowering safety Malcolm Jenkins into the slot and replacing him with veteran Corey Graham.

Jenkins and Graham are so assignment sound that Schwartz has no issues pulling that trigger with just a week of game-planning.

Jones is so talented, however, the feeling remains that the Eagles will throw him into the deep end against Matt Ryan, Julio Jones, and the Falcons to see if he can swim with sharks that have MVP and All-Pro on their resumes.

The easiest way to do that is inserting him into the slot.

"They have challenges just like everybody else," Schwartz said when asked about an inexperienced player handling the inside work earlier this summer. "If we had positions that we didn't feel that rookies or inexperienced players could play, we'd have a lot of positions open on the field. So, everybody's got challenges, whether you're a defensive tackle, whether you're a safety or a nickel. Their job is to do their job on the field."

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