2015 Miami Dolphins training camp preview

The Miami Dolphins open training camp on July 30 at Nova Southeastern University in Davie, Florida. Here's a closer look at the Dolphins' camp, which wraps up on Aug. 17:

Top storyline: Miami's top storyline is the progression of the passing game. In a strategic move, the Dolphins got rid of three of their top four receivers (Mike Wallace, Brian Hartline, Brandon Gibson) and their starting tight end (Charles Clay). The replacements are Greg Jennings, Kenny Stills, rookie and first-round pick DeVante Parker and former Pro Bowl tight end Jordan Cameron. The goal of Miami's front office was to acquire more athletic and physical receivers who better fit the skills of fourth-year quarterback Ryan Tannehill. Accuracy and ball placement have been issues at times for Tannehill. Sometimes, his throws are too left, too right or too high, and Miami's new receivers are better at adjusting and fighting for the football. Players such as Jennings, Parker and Cameron also have the ability to be prolific in the red zone. The Dolphins led the NFL last year in red zone trips but scored a touchdown only 54 percent of the time.

Position battles to watch: Although it doesn't sound sexy, Miami's biggest position battles this summer are happening at the two guard spots on the offensive line. Tannehill has been sacked 139 times in three seasons -- more than any active quarterback in that span -- and that has to stop this year, especially after Miami invested $96 million in its franchise player. Dallas Thomas and Billy Turner began the offseason as the starting left and right guards, respectively, but Miami did so much shifting by the time minicamp came around that it's hard to say any guard is 100 percent certain to start in Week 1. Jeffrey Linkenbach and rookie fourth-round pick Jamil Douglas also are firmly in the competition, and right now, it's anyone's game.

Veterans to watch: Jennings comes to Miami in an interesting spot. He's no longer the 80-catch, Pro Bowl receiver he once was with the Green Bay Packers. But Jennings, 31, also believes he's better than what he showed with the Minnesota Vikings last season. Jennings came to Miami to reunite with a familiar face in head coach Joe Philbin, who was Jennings' offensive coordinator in Green Bay. The Dolphins need Jennings to provide steady leadership and production. Parker is expected to miss most or all of training camp, which means Jennings will most likely start early in the season. A lot of eyes also will be on the health status of Cameron, who suffered multiple concussions last year and must stay healthy.

Rookies to watch: I need to see more from second-round pick Jordan Phillips. The former Oklahoma defensive tackle has promise but came to Miami with some questions about his motor and work ethic. Trench play is difficult to gauge in the spring when there are no pads and restricted contact. So I'm not going to jump to conclusions that Phillips didn't necessarily stand out in organized team activities and minicamp. Phillips is the type of plugger in the middle who must make his presence felt when the pads come on in training camp and the preseason. Phillips expects to be a backup this season behind starters Ndamukong Suh and Earl Mitchell. But Phillips could get several snaps a game off the bench if the rookie earns a role this summer. Also keep an eye on fifth-round pick Jay Ajayi, who is looking to spell starting running back Lamar Miller for carries.

Bubble watch: Former first-round pick and quarterback Josh Freeman is on the hot seat. He was mostly shaky in OTAs and had issues with his accuracy. However, Freeman did put together a solid couple days at minicamp to help his standing. Still, Freeman is third string, at best, and he's not expected to catch No. 2 quarterback Matt Moore. Freeman's best hope is to show the Dolphins enough to convince them to keep a third quarterback. Among other bubble players are running back LaMichael James, veteran cornerback Zack Bowman and second-year receiver Matt Hazel.

The Suh Effect: The early reviews for Suh have been excellent. Suh was dominant in the spring and looks to carry that over into training camp, the preseason and regular season. The Dolphins invested $114 million to sign Suh in free agency. He made about two or three "wow" plays per practice with Miami. In fact, Dolphins defensive coordinator Kevin Coyle told the team's website they've had to dial Suh back a bit in practices because he was causing too much havoc for the offense. Suh's presence and play have instilled confidence in his teammates on defense.

For daily updates at camp, check out the Miami Dolphins clubhouse page.