RENTON, Wash. -- During the offseason, the Seattle Seahawks took several steps to ensure that they'd have options at running back in 2016.

They brought Christine Michael back, and they used three of their 10 draft picks on the position. Three weeks into the season, they're looking for help.

The team signed veteran C.J. Spiller to a one-year deal Wednesday. He becomes the fifth running back on the 53-man roster, but only three are fully healthy. The addition is likely linked to C.J. Prosise's hand injury. Prosise played nine snaps in Week 1 but has been sidelined since.

Prosise can try to play with some type of wrap or brace on his hand, but that obviously would be difficult for someone counted on to carry and catch the football.

Asked when Prosise will be able to play without anything on his hand, coach Pete Carroll said, "Really not until it's healed. Those are six-week processes, so likely he'll have to wear something to protect him all the way through those six weeks. We're still a long ways away from that."

The injury occurred in Week 1, so based on Carroll's timeline, that would mean Prosise might not be 100 percent until Week 7.

The Seahawks drafted Prosise with the specific idea of having him be the third-down back, a role occupied by veteran Fred Jackson last season. But with him sidelined, they haven't had anyone to fill that role.

In Week 2, Thomas Rawls and Michael shared third-down duties. But Rawls (fibula) is sidelined for at least a few weeks. Michael has looked capable of being a three-down back, but considering the heavy workload he's going to be taking on, the Seahawks want to be able to spell him whenever possible.

Fifth-round pick Alex Collins was the third-down back last week, but he's more of a between-the-tackles runner. And the team re-signed seventh-round pick Zac Brooks to the practice squad. The Seahawks liked Brooks' receiving ability when they drafted him, but apparently they don't believe he's ready yet for a bigger role.

As a pure running back, Spiller's best days are almost certainly behind him. He carried just 36 times for 112 yards (3.11 YPC) last season with the New Orleans Saints. Even in Spiller's last season with the Buffalo Bills, he averaged 3.85 YPC.

Jackson played 15.3 snaps per game last season. He had only 26 total carries and caught 32 balls. That's the role Spiller will most likely be filling. If he shows he has some juice left, Spiller could see more touches than Jackson did last year, but this is still a specified role, and he's definitely more of a pass-catcher than a ball-carrier at this point in his career.

Last season, Spiller caught 34 of 42 targets (81.0 percent) and averaged 7.03 yards per reception. Many of his catches came in the flat or on wheel routes down the sideline. Spiller also has the ability to line up in the slot or out wide if the Seahawks want to use him that way.

Until Rawls and Prosise get healthy, look for Michael to get the bulk of the carries. Collins will likely rotate in. And Spiller will take over on third downs and be used in the passing game.