On one hand, Bush is coming off a down year. On the other hand, he was their best offensive playmaker, and leader in total touchdowns.
On one hand, they have seen enough out of Daniel Thomas to know he likely won't help much in their backfield. On the other hand, they haven't seen nearly enough out of Lamar Miller to draw any sort of conclusions about his ability to fill Bush's role.
There are a lot of questions, but there are two questions that reign supreme: should he be back, and will he be back?
By the numbers, it's tough to dispute he should not be re-signed, and recent reports agree.
Jason La Canfora of CBS Sports reported on January 25 that it's "highly unlikely" the Dolphins bring Bush back, citing his "ability to make explosive plays and contribute on special teams" as reasons why the market will be very kind to a player of his talents.
Barry Jackson of The Miami Herald reported on Wednesday that Bush "always intended to test free agency...barring the Dolphins making a surprisingly attractive offer."
Bush enjoyed a breakout 2011 campaign that saw him rush for 1,000 yards for the first time in his career, averaging five yards per carry along the way. Given more carries, he finished 100 yards shy of his total from last year and averaged 4.3 yards per carry.
Bush's numbers have taken a hit overall, but he is still an explosive threat for any offense that picks him up. He reeled off six runs of 20 yards or more, tied with four others for seventh-most in the NFL in 2012.
Bills nose tackle Marcell Dareus had an interesting quote about Bush on Dec. 23 after Bush rushed for 65 yards on 3.4 yards per carry in the Dolphins’ 24-10 win:
"Reggie really doesn't hit the holes he's supposed to hit," Dareus said. "He just makes whatever happen, happen."
The Dolphins' zone running game—which revolves around the same outside stretch play that Peyton Manning and the Colts ran to perfection for years—depends on decisive running and timing. The running back has to plant his foot, cutback and hit the right hole at JUST the right time, or the play breaks down.
Additionally, his injury problems throughout his career would be another red flag in regards to a long-term deal. The Dolphins have been fortunate to have lost Bush for just one game in 2011, but he wasn't the same for a long time after suffering a knee injury against the Jets.
Seems obvious that the Dolphins should move on, right? There is a caveat.
Simply, the Dolphins lack other options, despite having invested heavily in the position over the past couple of years.
In using a second-round pick on Daniel Thomas in 2011 and a fourth-round pick on Lamar Miller in 2012, the Dolphins have indicated they would like to move toward a younger stable of backs. That being said, Thomas has not proven himself worthy of an increased workload and Miller is a complete unknown due to the confusingly light workload he had last year.
Without Bush, who do the Dolphins have at running back? More to the point, who do they have on offense? Wide receivers Brian Hartline and Davone Bess hauled in a good deal of passes, but neither were the type of big-play threat general manager Jeff Ireland would like to have in the offense.
But with Hartline's contract up this year, and Bess' contract up next year, do the Dolphins want to go all-in on the same offensive skill position talent that led to them ranking 27th on offense in 2012?
Bush is aging, but he is not ancient. He turns 28 on March 2, 10 days before the free agency period begins. If the Dolphins could come to an agreement on a two-year deal, that might be ideal for them.
Bush, however, may not be so willing to accept such a short-term contract.
The Dolphins, meanwhile, may not be too thrilled about going to great lengths for a running back in a pass-happy West Coast offense.
With other major free-agent decisions to make in left tackle Jake Long, cornerback Sean Smith and Hartline, it wouldn't be surprising if Bush ranked rather low on the priority list.
The Dolphins could very well get lucky with a barren market for Bush. The very factors mentioned as to why the Dolphins might be wise to avoid bringing him back might be determining factors in other teams staying away. If that happens, Bush's value could dip to a point where the Dolphins might feel comfortable bringing him back.
Bush could return if he is unable to find a deal similar to the $4.5 million average he garnered with the Dolphins over the past two years.
With $35.8 million in cap space, the Dolphins could afford to get into a bidding match if they want to, but with so many other free agents coming up this season, and names like Bess, guard Richie Incognito, safety Reshad Jones and defensive tackle Paul Soliai becoming free agents in 2014, the Dolphins have to think not just for now, but for the long-term.
Investing top dollar in an aging back will probably not be at the top of the agenda, regardless of how important he's been to the offense over the past two years.
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. Unless otherwise specified, all quotes are obtained firsthand or via team press releases.