Ever the defense-minded head coach, Pete Carroll says he believes that an NFL roster can never have enough pass-rushers.

It's why his Seattle Seahawks spent a second-round pick on Frank Clark in 2015 even though they had recently extended Michael Bennett and Cliff Avril, and had Bruce Irvin under contract for another season.

Four years later, no reasonable analysis would conclude the Seahawks had enough proven pass-rushers even before they traded Clark and especially after they sent him to Kansas City for a first-round pick they used on defensive end L.J. Collier.

The Seahawks badly needed help there, and Ziggy Ansah, injured shoulder and all, was the best of the options still available in early May.

The Seahawks are taking a gamble on Ansah, but it's a necessary one. According to ESPN's Adam Schefter, the one-year deal he has agreed to includes a very reasonable $5.5 million in guarantees and the ability to earn another $8 million. So the Seahawks have some protection against his shoulder injury, which league sources told Schefter might keep Ansah sidelined through the start of the season.

But the Seahawks aren't hurting for immediate cap space even after making Russell Wilson the highest-paid player in NFL history. Trading Clark meant they no longer had to budget around his $17.128 million franchise tag. They'll free up as much as $4.8 million once they release Kam Chancellor and would gain additional cap relief if they do the same with Doug Baldwin.

Yes, the money the Seahawks are spending on Ansah could instead be used on extensions for Bobby Wagner and/or Jarran Reed. But with those players under contract for at least another season and the franchise tag at Seattle's disposal in 2020, adding a pass-rusher takes precedence.

Otherwise, the Seahawks would have sorely lacked firepower on the edge. That would have made life harder on a rebuilt secondary that might have only one starter -- safety Bradley McDougald -- with more than two seasons of NFL experience. The Seahawks got a career-best 10.5 sacks out of Reed last season -- tied for the fourth most among defensive tackles -- but no edge player on their roster had more than the 5.5 that Cassius Marsh got in San Francisco. Carroll has talked up 2018 draft picks Jacob Martin and Rasheem Green as players who should produce more this season, but for now they can't be counted on to be anything more than complementary pieces of a pass rush.

The same is true for Collier.

Given how strong of a draft it was for edge rushers, it was a surprise the Seahawks emerged with only one of them among their 11 selections. But even if they had doubled up on that position after taking Collier 29th overall, there's only so much production they could expect to get from a draft pick right away.

Over the past 10 seasons, only 15 rookies have produced at least eight sacks. Of that group, nine were selected in the first half of the first round, including Irvin (15th overall in 2012) and Ansah (fifth overall in 2013). Only six times in that span did a rookie produce 10-plus sacks. Aldon Smith in 2011 is the only one with at least 13, which is what Clark produced for Seattle last year.

It would be asking a lot of Collier just to match Irvin's franchise record of eight sacks as a rookie, let alone top it.

It was thus a certainty that the Seahawks would add to their pass rush after the draft. Shane Ray was among the available names but didn't offer the same upside as Ansah, who has 48 career sacks in 80 games and a Pro Bowl on his résumé. The same is true for Nick Perry, who also visited the Seahawks and, like Ansah, is coming off an injury.

The Seahawks plan to use Collier as a five-technique, which is the bigger of the two defensive ends in Carroll's defense and the one who primarily plays on the strong side. He'll slide inside in some passing situations, a la Bennett. The Seahawks see Ansah as an ideal fit for their Leo end, previously manned by Chris Clemons, Avril and Clark.

There's some symmetry between the Seahawks' additions of Avril in 2013 and Ansah now. Both came to Seattle after playing on the franchise tag with the Lions the previous season. Avril and Bennett went on to become two of the best free-agent additions in Seahawks history, both ranking in the top 10 on the franchise's all-time sack list despite playing only five seasons in Seattle.

The Seahawks would take just one productive season from Ansah. They need it, which is why he's a worthwhile risk.