The offseason program is underway with the Miami Dolphins.

Let’s open the Twitter mailbag to see what’s on the minds of Dolphins fans:

@JamesWalkerNFL Who are your picks for our two starting outside WRs and slot?

— Adam (@A__J__B) May 21, 2015

James Walker: Good question, Adam. This will be one of the best competitions to watch this summer, and the truth is even the Dolphins aren't sure at this point. For starters, I project Kenny Stills to be one starting receiver. He has the speed and quickness the team needs on the outside to try to replace Mike Wallace. The main competition will be between veteran Greg Jennings and rookie first-round pick DeVante Parker, and I can make a case for either receiver. Jennings is a veteran with championship experience and knows what he's doing. I wouldn't be surprised if head coach Joe Philbin, who often leans toward veterans, relies on Jennings early on while Parker gets used to the NFL game. However, Parker is a dynamic first-round pick with a lot of talent. I was really impressed with him during four practices in rookie camp. If Parker continues to grow during the next 3-4 months, it's going to be hard to keep him out of the lineup. For me, it's Stills on one side and a pick-'em race between Jennings and Parker that will be decided in training camp.

@JamesWalkerNFL Do the #Dolphins have one of the best defensive fronts in the NFL?

— Phillip Dillingham (@phillipdilling1) May 21, 2015

Walker: I'm not ready to go that far, Phillip. There are still major concerns about the linebacker position. One starting spot at outside linebacker is wide open, and I don't like Misi's fit as a middle linebacker. He's just an average player when moved out of position. So you essentially have two holes at linebacker. Yes, Ndamukong Suh's presence and playmaking ability will help the linebackers. But there is still responsibility on those three players to make sure tackles and cover well against the pass. I didn't see enough of that last year.

@JamesWalkerNFL With multiple changes to both sides of the line, which settles in and plays (well) together sooner, offense or defense?

— Terence Coughlin (@TCoughlin) May 21, 2015

Walker: With a doubt, Terence, it's the defensive line. For one, Miami knows its starting front four of Suh and Earl Mitchell at defensive tackle and defensive ends Cameron Wake and Olivier Vernon. That group is working together, starting in May, and will build months of chemistry leading into September. Miami's offensive line is still in flux. Left tackle Branden Albert is still rehabbing. He's expected back for Week 1, but Albert won't be on the field to get much practice time with his teammates likely until late summer. Both guard positions have competitions and players will be filing in and out to get reps. The Dolphins' offensive line will be unsettled until late in the preseason.