Who’s going to carry the ball?

That’s one of the biggest questions surrounding the Miami Dolphins as they make their way through the OTAs, into next week’s mini camp and down the road to training camp.

A year ago it was a lot of Reggie Bush and some of Daniel Thomas and Lamar Miller. But now Bush has motored to Detroit and there is an interesting group of running backs vying for playing time. All young. All with solid credentials. All without much experience on this level.

All wanting the ball.

Listen to Coach Joe Philbin and he’ll tell you that the competition is wide open. How wide open? So wide open that every back on this roster will receive a legitimate shot at playing time. That’s the thing about Philbin. Once you step through his doors, it doesn’t really matter what you have done in the past. Every back resides on equal footing regardless of the path he took to get here.

“I like this group,” Philbin said. “They each have a different skill set. I’m excited about what I’ve seen so far. Now the proof is in the pudding, but this has a chance to be a very good group.”

It is clear already that with the emphasis in Philbin’s system pointed so heavily toward the passing game that these running backs will be counted upon to both catch passes and protect the quarterback. I don’t expect this to be a grind-it-out team. But in order to be as explosive on offense as the Dolphins hope to be, it is imperative that the running game be productive and proficient.

As for the competition currently in progress, I expect one running back to emerge above the others and then one or two to see significant playing time.

There are those who believe that second-year back Lamar Miller has the inside track for the starting job because he was Bush’s back-up much of last season and because he is brimming with potential. I can see that rationale.

Miller gives the Dolphins a real big-play threat at that position and appears diverse enough to handle several roles. That he averaged just under 5 yards a carry last season says plenty.

“My goal is to rush for 10,000 yards in my career but I know I have a long way to go,” Miller says. “These are good players I’m competing against and I know I’ve got to get better every day. That’s what I’m all about right now.”

Nobody, though, is handing Miller the job.

There are six running backs on the Dolphins roster right now and each of them offers an intriguing option. Each of them will get his shot.

In addition to Miller, you’ve got Daniel Thomas, the old man of the group entering just his third season. Thomas has been plagued by injuries his first two seasons and, when healthy, has shown to be both tough and productive. I like his skill set. I like his size at 6-1, 228. But Thomas must show that he can stay healthy, must show that his body can hold up to the grind of a 16-game marathon of a season.

Then there is Mike Gillislee, a fifth-round pick coming off an excellent senior season at the University of Florida. Gillislee is a smash mouth type of back, a player who would just as soon run over you as around you. He can also block and catch passes, imperative traits in this offense.

Right now, Gillislee is just trying to get a feel for the pace of these Dolphin practices.

“The SEC is fast, but this is even faster,” he said. “My goal right now is to learn something every day and do enough to make the team.”

It figures that Miller, Thomas and Gillislee will go into training camp as the top three backs, but the other three backs, at least at this point, should not be overlooked.

Marcus Thigpen made a name for himself last season as a kick returner, but the coaching staff likes his speed, big-play ability and potential. He certainly has the tools to make things interesting.

Jonas Gray was signed by the Dolphins a year ago as a long-term project who was fighting his way back from a knee injury in college at Notre Dame. He is healthy now, has shown some good things in the offseason workouts and when you watch him run, with his powerful 5-9, 225-pound physique, you see why the coaching staff wants to see more.

Finally, there is undrafted rookie Cameron Marshall who put together some impressive numbers at Arizona State, rushing for 2,700 yards and 38 touchdowns in his four seasons there. At this point, you have to consider him a long shot, but with Philbin’s wide open door policy, all he needs is one big run to justify additional attention.

I haven’t checked every other roster, but I’ve got to believe this is the youngest group of running backs in the league. I mean three of the six are waiting for their first NFL carry and Thigpen has just one carry. That leaves Miller who had 51 carries last season and Thomas with his 256 carries over two seasons.

Who’s going to carry the ball this season? It’s far too early for predictions. This race is close with many more challenges ahead. That the Dolphins did not spend large dollars on a free agent running back this offseason shows you the confidence that they have in these players.

Now, it is up to them to show that this confidence was justified.