5 Newcomers Who Will Play Biggest Roles for the Miami Dolphins

As is the case with any change of scheme and regime, the Miami Dolphins have a lot of turnover on their roster, and therefore, will be counting on many of their new additions to quickly find roles in the defense.

Some roles will be bigger than others—free-agent cornerback Richard Marshall will probably see a lot more time on the field than seventh-round defensive tackle Kheeston Randall.

Nonetheless, a sound argument could be made for many newcomers to have a big role—after all, the team probably wouldn't have brought in said player otherwise.

Here, though, are my five predictions for the biggest roles among newcomers.

Lamar Miller

Reggie Bush has dreams of the rushing title, and while his explosive potential could make him a contender for the yards-from-scrimmage title, that's also dependent on him getting a large majority of the snaps (and making the most out of them). Enter rookie running back Lamar Miller, a fourth-round pick out of Miami who has big-time open-field potential.

As Bleacher Report Dolphins featured columnist Alex Miglio pointed out in our debate, the Dolphins could be heavily utilizing their running backs under new offensive coordinator Mike Sherman:

"

When Sherman was the head coach for Green Bay, he helped Ahman Green have his most productive years, topping 1,000 yards each season from 2000-2004, including an 1,833-yard season in '03. He also caught 50-plus catches in four of those five seasons, dropping down to 40 in '04. Heck, even Samkon Gado rushed for 582 yards in just eight games in 2005 after Green was injured. ...

Fast-forward to Texas A&M where he coached the past four seasons, and you will see another positive trend. ...

[Kansas City Chiefs running back Cyrus Gray] topped 1,000 yards in each of his first two seasons on 198 and 200 carries, respectively, for Sherman at Texas A&M, and he averaged over five yards per carry (YPC) for his career in college.

"

He was referring to Bush specifically, but the increased opportunities could mean big things to come for the rookie.

Richard Marshall

The Miami Dolphins had a solid defense last season that ranked sixth in scoring, but their defensive backfield left a lot to be desired. Cornerback Sean Smith struggled to the tune of 793 yards and a 90.7 passer rating on throws his direction according to Pro Football Focus.

That's where Marshall comes in; the then-Cardinals defensive back gave up just 394 receiving yards and a 64.9 passer rating on throws his direction. He has played all 16 games in each of his six seasons in the league, but started just nine in 2011, as he was not initially a starter, but only earned the role later in the season.

Amid some speculation as to whether he'll play cornerback or safety head coach Joe Philbin made it clear that Marshall will be a cornerback, according to the Miami Herald. Now, he will play a big role in helping the secondary improve after allowing 7.2 YPA and an 83.7 defensive passer rating in 2011.

Tyrell Johnson

Safeties Chris Clemons, Tyrone Culver and Reshad Jones have been with the team for awhile, but none of them has brought the Dolphins a steady presence on the back end of the defense.

While Johnson hasn't played a significant part of the Vikings defense over the past two seasons (18 games, five starts, 414 snaps), he was a significant part of two successful seasons in 2008 and 2009 (31 games, 22 starts, 1,491 snaps) in which the Vikings fielded a top-10 unit on defense.

If Johnson can stay healthy after two seasons marred by injury, he could be a big part of the Dolphins defense. Still, he wasn't playing much even when healthy over the past two seasons, but if he's better than what the Dolphins have (and at his best, that appears to be the case), the Dolphins could be relying on him on the back end of their defense in 2012.

David Garrard

We don't know who will win the Dolphins' starting quarterback job.

Whether he is a starter or a back-up, though, David Garrard could play a big role. The Dolphins drafted Ryan Tannehill in the first round, and the team would love nothing more than to have an experienced veteran quarterback in his ear all season long.

At $3.35 million, the Dolphins brought in Garrard for a reason. Whether that reason was to be the starter or to be a mentor remains to be seen, but either way, he will play a big role for the Dolphins in 2012.

But at that price, the Dolphins may not find his role on the bench to be big enough to warrant the money.

Jonathan Martin

After protecting quarterback Andrew Luck's blind side for three years when the two were together at Stanford, Martin is familiar with bearing a heavy burden at offensive tackle week-in and week-out.

The Dolphins are looking to implement a new zone blocking scheme on the offensive line, which calls for smaller, lighter offensive linemen who are quick on their feet. The Dolphins took Martin in the second round of April's draft, a strong indication that they see in him the tools that will be needed to succeed in their offense.

That's more than can be said for many of Miami's offensive linemen, and there could be plenty of early opportunities for Martin to make an impact.

Erik Frenz is the AFC East lead blogger for Bleacher Report. Be sure to follow Erik on Twitter and "like" the AFC East blog on Facebook to keep up with all the updates.