JACKSONVILLE – Another day, another defensive uncertainty.

This time, the uncertainty is not on the line or at linebacker, but in the secondary – and it involves one of the Jaguars' most reliable defensive players.

Alan Ball, a veteran cornerback who has started 22 of 23 games since joining the Jaguars in the 2013 offseason, missed practice Wednesday while receiving a second opinion on a biceps injury. His status is uncertain for Sunday.

"I would say he's doubtful," Bradley said of Ball Wednesday as the Jaguars (1-6) prepared to play the Miami Dolphins (3-3) at EverBank Field Sunday at 1 p.m.

With Ball uncertain, second-year cornerback Dwayne Gratz likely will start in Ball's spot with Demetrius McCray remaining the starter on the other side.

Gratz, a third-round selection in the 2013 NFL Draft, started the first four games of the regular season before sustaining a concussion against San Diego. He has backed up McCray the last two games, playing about half the number of snaps.

The news regarding Ball came two days after the Jaguars announced that two other key defensive players are out for extended periods, with middle linebacker Paul Posluszny out for the season with a torn pectoral muscle and defensive end Andre Branch out at least six weeks with a groin tear.

With J.T. Thomas moving from the starting Otto outside linebacker position to replace Posluszny in the middle, Dekoda Watson likely will start and play the majority of the snaps at the Otto. Watson was signed as an unrestricted free agent from Tampa Bay in the offseason to play the Otto position, but missed the offseason and much of training camp with a groin injury.

"Camp plays a tremendous role," Watson said. "I feel like if I would have had that I would have been a lot better off and a lot further along, but at the same time there's no point in crying over spilled milk. I just have to continue to strive toward victory."

LaRoy Reynolds started the first three games at the Otto position, but Bradley said on Wednesday the position on Sunday likely will be "more Dekoda."

The absence of Branch likely will mean an increased role for reserve end Ryan Davis, and Bradley said rookie defensive end Chris Smith – signed from the practice squad Monday when Posluszny was placed on injured reserve – also could be active Sunday.

Bradley called Wednesday's work productive, in part because of the faces in new places.

"I thought they did a nice job, especially on the first day," Bradley said. "I'm sure the meetings were even more attentive because of that, especially in the linebacker room."

Also around the Jaguars:

*Cornerback Aaron Colvin practiced on a limited basis, his first practice since being selected in the fourth round of the 2014 NFL Draft from Oklahoma. Colvin spent the first seven weeks of the season on the Physically Unable to Perform list, and the Jaguars have 21 days from Wednesday to activate Colvin or place him on injured reserve. Bradley said while the Jaguars won't necessarily take the entire 21 days it's "very" doubtful that Colvin will play Sunday. "I think the biggest thing for him will just be football shape, going play after play," Bradley said. "We're not going to slow the whole process down and say, 'Hey, let's wait a full three weeks.' If he's ready to go and he can add and help our team, we're going to take a serious look." …

*Center Luke Bowanko practiced on a limited basis with an ankle after finishing the victory over the Browns with the injury. Safety Craig Loston practiced on a limited basis after sustaining a hamstring injury Sunday. …

*Running back Toby Gerhart returned to practice for the first time in two weeks after missing the last two games with a foot/ankle injury that has hampered him since Week 1. Bradley after practice said Gerhart looked good in the two-hour-plus session. "He said it felt pretty good," Bradley said. "The last two weeks have been tough on him, but today he felt a lot better. He felt like it was beneficial for him to have that time off." …

*Rookie linebacker Telvin Smith on being named AFC Defensive Player of the Week by the NFL on Wednesday: "It's nice, just to say I was able to accomplish that. That's big, not only for me but for the defense. To have players making plays like that and getting nationally noticed, let's keep going. Hopefully, we'll have a few more players up there." Smith on Sunday registered a sack, forced fumble, interception and two passes defensed in a 24-6 victory over Cleveland. …

*Jaguars running back Denard Robinson, asked if he believed his "ceiling" in the NFL is still pretty high: "That's the biggest room in my house, is the Room for Improvement." …