The Seattle Seahawks' backfield was so depleted by the end of last season that they brought 33-year-old Marshawn Lynch out of his second NFL retirement. That was after Chris Carson, Rashaad Penny and C.J. Prosise suffered season-ending injuries within a 15-day span.

Carson has finished two of his first three seasons on injured reserve. Penny is in serious danger of missing much of the first half of the coming season. Prosise is a free agent and has the longest injury history of them all.

That helps explain why the Seahawks are adding Carlos Hyde even though Carson is coming off consecutive 1,000-yard seasons and even given their recent first-round investment in Penny.

And there's this: Seattle leads the NFL in non-dropback percentage since coach Pete Carroll arrived in 2010, per ESPN charting. That metric measures rushing percentage, excluding scrambles and kneel-downs, to provide a truer indication of how often an offense looks to hand the ball off. The Seahawks are second over the past two seasons even as Russell Wilson has cemented his status as one of the game's best quarterbacks.

Carson is still the primary option in Seattle's backfield and is on track to be ready by the start of the season. But with his injury history, the concern over Penny's availability and the degree to which Carroll -- for better or worse -- wants to run the ball, the Seahawks felt they needed another veteran to reinforce their backfield. They made Devonta Freeman an offer he didn't take, leading to the one-year deal with Hyde last week.

Lynch said his agent had been in talks with the Seahawks, but it's fair to wonder how much interest he'd have in going through another training camp just to be the second or third option. An in-season emergency like what the Seahawks experienced in December seems to be the scenario in which another Lynch return would make the most sense -- especially since Hyde has joined the mix.

Here's a look at the Seahawks' top five tailback options:

Chris Carson. He didn't need surgery on the hip fracture he suffered in Week 16. Before that, Carson remained Seattle's primary option despite seven fumbles and Penny's second-half emergence, so don't expect him to cede any more carries to Hyde than he would to a healthy Penny. Carson is still Seattle's RB1 as he enters the final year of his rookie contract. His 2,381 rushing yards over the past two seasons is fifth most in the NFL. That Carson has only 57 receptions in that span -- tied for 32nd among running backs -- is more of a function of Seattle's offense. He has the receiving skills to be a three-down back, but his rugged running style and injury history make that less feasible.

Carlos Hyde. While Freeman would have been exciting, Hyde might make more sense for what the Seahawks want to do offensively. At 6-foot and 229 pounds, he's another big body who can execute Seattle's power running game when Carson is off the field in a way that the much smaller Freeman could not. Hyde caught a career-high 59 passes with the 49ers in 2017, so he's a capable receiver out of the backfield. But expect more of his work to come as an early-down complement to Carson -- at least until Penny comes back. The Seahawks prefer to structure veteran contracts with roster bonuses that are earned only if a player is active on game day. That would be a way for Seattle to save some of that $4 million if Hyde becomes less of a necessity later in the season.

Rashaad Penny. The Seahawks believe Penny is likely to begin the season on the physically unable to perform list, which he'd have to remain on for the first six weeks (Seattle's bye is in Week 6). Penny was starting to emerge when he tore his ACL and suffered additional damage to his knee in Week 14, requiring reconstructive surgery. He combined for 236 all-purpose yards and three touchdowns in the two weeks prior, which included a 58-yard TD run during the most productive game of his career. Penny has been more of an early-down complement to Carson in his two seasons (151 snaps on first down and 119 on second, per ESPN charting) than a third-down back (43 snaps).

DeeJay Dallas. The fourth-round pick from Miami might benefit most from Seattle adding Hyde instead of Freeman. After all, Freeman would have factored in heavily on third down given his skills as a receiver, which might be a reason why Wilson wanted him. That's the role that Dallas is most likely to fill. The Seahawks think highly of Dallas' pass protection and his ability to catch the ball out of the backfield as a converted wide receiver, two skills required for third-down duty.

Travis Homer. Dallas' teammate in college, the 5-10, 202-pound Homer was active for every game as a rookie last season mostly because of his special-teams contributions. He was pressed into starting duty in Week 17 after Carson and Prosise went down, averaging 6.2 yards per carry in that game but only 1.1 in the wild-card round before Seattle turned to Lynch. Special teams and a season's worth of experience will give Homer an advantage over undrafted rookies Patrick Carr (Houston) and Anthony Jones (Florida International) for the fourth and potentially final tailback spot, assuming Penny is on PUP. The Seahawks carried four tailbacks on their 53-man roster for most of last season. That doesn't count veteran fullback Nick Bellore, who's under contract for another season.