Can you trust either Dolphins RB?

What do we make of the Dolphins' two-headed rushing attack?

Ronnie Brown, Ricky Williams. Ricky Williams, Ronnie Brown.

Two familiar names, two veteran backs, two key cogs in the Dolphins' offense. Yet both serve as frustrations to the other's fantasy owners. The natural instinct, for many of us, is to say that one is a natural handcuff for the other, except that's improper use of the terminology. A "handcuff" -- detailed excellently by colleague Eric Karabell -- is a backup running back, a player not expected to start or provide many fantasy points, behind a starter who's a clear fantasy option. The purpose of picking such a player is to protect your investment in the starter; in the event of catastrophic injury to said starter, the handcuff should slide right in and presumably provide similar production.

Obviously, the first thing the handcuff hunters will say in reply is that after Brown, who managed three games of 20-plus fantasy points the first five weeks of 2009 and averaged 13.1 for the year, was lost for the season, Williams stepped in with four double-digit fantasy performances and an average of 12.6 points the final seven weeks. Had you rostered both players from the start of the year, you'd have been fully protected when Brown was lost.

The problem with that argument, however, is that it diminishes Williams' contributions before Brown got hurt. In those nine healthy Brown games, for instance, Williams averaged 12.1 fantasy points, well within range of his level of production after Brown went down, and the division of the rushing workload was as follows: 48.5 percent Brown (147 carries), 34.7 percent Williams (105), 7.9 percent other running backs (24), 6.6 percent quarterbacks (20), 2.3 percent receivers (7).

In short, Brown and Williams aren't handcuffs; they're tandem backs, somewhat like DeAngelo Williams and Jonathan Stewart are tandem backs for the Carolina Panthers. But there are critical differences between the Dolphins' duo and that of the Panthers, and it helps explain why both Panthers backs are being selected, on average, earlier than either Dolphins back: Neither Dolphin is as talented as either Panther, and both Dolphins present more risk than either Panther.

The case against Ricky Williams

This is the easy one, and while Williams' 60.6 average draft position (58th overall), lowest of the quartet, might hint that fantasy owners are already aware how facile the argument, it's often simple for people to get carried away with facts, like this one: Ricky Williams had more total fantasy points in 2009 than either DeAngelo Williams, Jonathan Stewart or Ronnie Brown.

I'm going to assume you're already familiar with the rationale behind not drafting strictly according to 2009 numbers and instead remind you of this: Ricky Williams is 33 years old and he has 2,164 career carries on his legs.

You can count the number of running backs who have managed at least 800 rushing yards, eight rushing touchdowns or an average of 4.0 yards per carry (minimum 100 attempts) in a season begun after their 33rd birthdays on two hands; only nine have done it. You can also count the number of running backs who have managed at least 1,000 rushing yards or 10 rushing touchdowns in a season begun after their 33rd birthdays on one hand; exactly five have done it. Here's the full list:

Williams' career workload is also a troubling number, as last season he became the 32nd player in NFL history to cross the 2,000-carry threshold. Of the previous 31 to do it, only nine had a greater yards-per-carry average after 2,000 than before it, and nine averaged more touchdowns per carry after 2,000 than before it. Durability also becomes an increasing concern after that point; the 31 players with 2,000-plus career carries averaged only 45 more games played apiece after getting there, and only four others remain on active NFL rosters: LaDainian Tomlinson, Fred Taylor, Thomas Jones and Clinton Portis, in addition to Williams.

Missing the 2006 season, most of 2007 and being limited to 45 games and 575 rushing attempts combined the past five seasons might have helped Williams maintain fresher legs, which could explain his surprisingly productive finish to 2009. But even if that's your belief, closer examination of his 2009 game-by-game performance reveals a somewhat disturbing trend:

Those splits do dismiss the fact Williams' most favorable matchups came in Weeks 10-12, when he faced three of the 11 worst run defenses in the NFL, but that yards-per-carry drop-off is troubling. Might it be that Williams was a perfect fit for a tandem role while Brown was healthy, but when pressed into a starting role, he began to wear down more quickly? It's certainly possible.

The case against Ronnie Brown

It's another obvious one: He's coming off Lisfranc surgery, a challenging operation from which to recover -- one detailed well by Stephania Bell -- and one that requires careful management all the way through the rehabilitation process. While all reports on Brown's recovery have been positive, it's a worry that he has had two major surgeries the past three seasons -- his 2007 was cut short by ACL surgery -- and could be classified as an "old" 28.

The Dolphins surely know this, and will undoubtedly use Williams to ease some of the physical strain on Brown during his comeback campaign. That rushing-attempt breakdown quoted above is especially relevant and might even overshoot Brown's projected 2010 usage; it wouldn't be surprising if he doesn't even exceed 40 percent of the team's total rushing attempts or 55 percent of the ones between him and Williams. Simply put, Brown can't be counted on to maintain the workload of a player who, before being lost for 2009, was on pace to finish among the top 10 running backs in fantasy.

So is there a case for either?

A large number of fantasy owners might simply assume that such a tandem arrangement will paint one of the backs into a between-the-20s option, with the other handling goal-line work, if only because that seems a popular assumption in a committed backfield. Fortunately, that shouldn't be a worry with Brown or Williams; in the nine weeks the two were on the field last year, Brown had eight rushing scores and Williams six, and the Dolphins weren't afraid to toss either back out there in a goal-line situation.

Heck, even if you worry that Brown's fresh-off-surgery status might tempt the Dolphins to declare Williams their goal-line back, remember that in 2008 Brown had 10 scores to Williams' four, and if you look at 2008-09 numbers combined, Brown had 36 rushing attempts from within the opponent's 10-yard line to Williams' 32, and that was with Brown playing nine fewer games. Both will matter in terms of touchdown potential.

Brown can also point to respectable comebacks by three other running backs who had Lisfranc surgeries within the past decade:

While none of that trio should send shockwaves through the fantasy world, they at least offer hope of a full, healthy recovery by Brown, and his top-10 potential during the weeks he was on the field a year ago demonstrates the level of his upside. He's among the riskiest selections at his position, hence the fifth-round ADP (46th, 49.5), but he's also capable of being an every-week starter in the best-case scenario.

Williams, meanwhile, has a definitive role on this team, but at his age he's more suited to play a slight second fiddle to Brown. Couple that with Williams' career workload and rapidly advancing age, and he's a flex-play capable back, but one who lacks much upside. His downside might not be quite as great as Brown's, but he can't match Brown in terms of upside.

Maybe neither back amounts to more than flex-play status, a label typically reserved for backs who finish in the Nos. 21-30 range at their position. But based upon positive marks for Brown during his comeback, and Williams' advancing age, Brown might be a fairly attractive selection compared to his ADP, while Williams might be a bit of an overdraft in the sixth round.

In short, both matter, but neither is free of causing his share of headaches.

Tristan H. Cockcroft is a fantasy football analyst for ESPN.com. You can e-mail him here, or follow him on Twitter @SultanofStat.