GREEN BAY, Wis. -- Eddie Lacy visited three teams desperate for a running back: the Seattle Seahawks, Minnesota Vikings and his old club, the Green Bay Packers.

Yet he's still on the market and could be for at least a little longer.

The same could be said for many of the free-agent running backs.

Several factors are at work.

None of the available big-name backs has signed anywhere yet. There are four of them among the ESPN Top 150 free agents: Latavius Murray (No. 28), Lacy (30), Adrian Peterson (39) and LeGarrette Blount (91). They're all still on the market. So is Jamaal Charles. Much like in the draft, when there can be a run on a certain position, perhaps once the first running back signs, the rest will quickly follow.

Here's how one NFL agent summed up the free agent running backs and why they're all still on the market: Each one has an obvious downside, there's no perfect candidate, teams don't like to pay running backs who have been injured and the money is likely less than what they and their agents hoped.

Lacy wrapped up his three visits on Monday, when he spent part of the day at Lambeau Field. It was presumably more of a medical check than anything else. He's four-and-a-half months removed from ankle surgery and said last month that he hoped to be able to run and work out for teams by now.

While one Packers free agent, guard T.J. Lang, was able to get a deal done with the Detroit Lions despite coming off hip surgery that may keep him out for much of the offseason program, perhaps teams would rather wait until Lacy can work out and pass all the medical tests before they sign him.

Whatever the case, the Packers need a running back to go along with Ty Montgomery. The only other back they have in the fold is Don Jackson, who was tendered as an exclusive rights free agent.

There's been no indication that they're interested in any of the other veterans on that free agent list. If Lacy gets away, then they maybe will be forced to at least consider a visit for someone like Peterson, who also visited the Seahawks but left without a contract.