The biggest position battles entering training camp for the Dallas Cowboys were starting cornerback, inside linebacker, No. 2 running back and backup quarterback.Saturday night’s 34-13 preseason win at Arizona featured some notable performances in all four areas.CornerbackShavon Revel has been having an excellent camp. Not only has his surgically-repaired knee looked healthy, but his overall confidence seems to be growing by the day. He made the first big play of the game Saturday when former Cowboys wide receiver Simi Fehoko slipped and Revel intercepted the Gardner Minshew pass. Revel returned the ball 22 yards to the Arizona 12, and Dallas took a 7-0 lead three plays later.DaRon Bland has one of the outside starting cornerback spots locked up. Revel is battling Cobie Durant for the other. Saturday was likely another confidence-booster for last year’s third-round pick. Regardless of that battle, both players are expected to play a lot this season. The cornerback depth isn’t great, but the top three spots look solid.Top Plays from Cowboys @ CardinalsInside linebackerJaishawn Barham didn’t play in last week’s preseason opener as he was working his way back from a groin injury early in camp. He played Saturday and looked every bit the player the Cowboys have been raving about. Barham pressured the quarterback, had a tackle for loss and a team-high five tackles in the first half. The third-round pick looks like he will have an immediate impact. Even if Dallas goes with DeMarvion Overshown and Dee Winters as its starting inside linebackers to open the season, Barham will get on the field. He’s too good of a playmaker to keep on the sideline.Barham can make plays in all areas, but he’s best around the line of scrimmage. He showed on several plays against the Cardinals that he’s likely going to be a nightmare for opponents to block. Inside linebacker was a major position of need this offseason. Missing out on a big name in free agency looked like it would be an issue. But if Overshown can stay healthy and Barham can play like he did Saturday, the Cowboys might be just fine.Running backJavonte Williams is the obvious lead back. He’s had a good camp, looking ready to repeat the strong season he had a year ago. But the No. 2 spot has been a competition the last four weeks with no one really separating themselves.Malik Davis seems to be the player the Cowboys are most comfortable with in that role at the moment. He started and played well, carrying five times for 29 yards and catching one pass for an 8-yard touchdown. But Jaydon Blue, who has the higher upside, also played well after Davis came out of the game. Blue carried 15 times for a game-high 75 yards. His quickness and athleticism were on display. The Cowboys just need to see more consistency from the second-year player.My prediction is that Davis starts the season as the No. 2 back but Blue takes it over during the season. I think the Cowboys end up keeping four running backs: Williams, Davis, Blue and Hunter Luepke.QuarterbackJoe Milton was the star of the night. The backup competition between Milton and Sam Howell saw Howell start last week and play the entire first half. Milton played the entire second half. On Saturday, those roles were reversed. Milton started and was outstanding, playing the entire first half. He was confident and calm in the pocket. He bought time with his feet to complete some monster throws.His deep ball up the left sideline to Jonathan Mingo was perfect, resulting in a 53-yard touchdown. And he never came close to turning the ball over. Milton finished 9 of 13 passing for 179 yards, two touchdowns, a 151.4 passer rating and added a short TD run. Milton’s confidence seemed to be growing by the day during camp. He played well last week. But his performance Saturday will make it difficult for Howell (7 of 10 for 65 yards with an interception) to jump him. Maybe the Cowboys keep three quarterbacks, but if they go with only Dak Prescott and a backup, Milton should be that player.“Joe has put together two really, really good halves,” Cowboys coach Brian Schottenheimer said after the game. “Sam really made one mistake, (the interception) down in the red zone. He kinda got fooled on one and turned it over. That can’t happen. But this is long from over. We’re going back to Frisco, thankfully, get a chance to be home and put some more training camp days in. You got to give Joe his credit. He’s played really well the last two games, but we have a lot of confidence in Sam as well.”Jonathan Mingo’s 53-yard TD reception against the Cardinals on Saturday is another reason Cowboys coaches will have a difficult decision at receiver. (Norm Hall / Getty Images)Wide receiverOne reason the Cowboys might not be able to keep three quarterbacks is because they could have to keep six wide receivers. CeeDee Lamb, George Pickens, Ryan Flournoy and KaVontae Turpin are roster locks. The fifth spot is coming down to veteran Jonathan Mingo and undrafted rookie Camden Brown. Brown has been more impressive, making highlight plays just about every day in practice and in both of their preseason games. But Mingo has also been playing well. This could be one of their most difficult roster decisions.Starters on SaturdayOn offense, the Cowboys went with Milton, Davis, Mingo, Brown, WR Tyler Johnson, TE Luke Schoonmaker, LT Drew Shelton, LG Trevor Keegan, C Nick Leverett, RG Ajani Cornelius and RT Nate Thomas.On defense, it was OLB Malachi Lawrence, OLB James Houston, DT L.T. Overton, DT D.J. Withers, DT Jay Toia, Barham, ILB Shemar James, Revel, CB Ameer Speed, S Alijah Clark and S Julius Wood.“The wins are great,” Schottenheimer said. “I’ve always thought, because my dad said it, the preseason record is never remembered. But I think what we’ve shown the last two games is there’s a play style about this team, whoever’s in the game, and that’s one of physicality, effort, playing together, and I do think that we played that way tonight for really four quarters, and I’m proud of the guys for that.”