Much of the Seattle Seahawks offseason has been focused on building depth on their roster.

The team won the NFC West last year and lost just two starters in free agency: linebacker Mike Morgan and right tackle Garry Gilliam.

Pete Carroll and general manager John Schneider talk often about finding players with unique attributes. That philosophy is part of what led them to draft 6-foot-6 defensive tackle Malik McDowell in the second round. They could have gone cornerback or offensive line with the 35th pick. But the Seahawks didn't see another pass-rushing, three-technique defensive tackle like McDowell in the draft.

The philosophy also presents a challenge in building depth. Last year, when Earl Thomas went down, the Seahawks' pass defense fell apart. Seattle allowed 12 touchdowns with just one interception when Thomas was sidelined. His unique attributes are his range and instincts. Put simply, it's nearly impossible to find another safety who can come close to playing at Thomas' level in the Seahawks' scheme.

The same can be said for other unique players such as Michael Bennett, Bobby Wagner and Richard Sherman.

Back in March, I asked Carroll if building depth is especially difficult for the Seahawks, given his philosophy of finding players with such unique attributes.

"If we were trying to make everybody like them, yeah because they are one-of-a-kind players," he said. "But we see attributes from other players who play like them. We don’t expect guys to do the same as somebody else. We expect them to be who they are and then we just try to figure it out. Fortunately, our staff is very experienced and been around enough to have enough in our arsenal to I think adapt and adjust to guys."

Thomas missed five games and the playoffs last season. Bennett missed five games but was back for the postseason. Russell Wilson didn't miss a start but played through three injuries. Thomas Rawls, C.J. Prosise, Kam Chancellor and Tyler Lockett each missed time due to injuries.

Overall though, when compared to other teams around the league, the Seahawks were relatively healthy. Football Outsiders' Adjusted Games Lost (AGL) metric is described as follows:

We are able to quantify how much teams were affected by injuries based on two principles: (1) Injuries to starters, injury replacements and important situational reserves (No. 3 wide receiver, nickel corner, etc.) matter more than injuries to benchwarmers; and (2) Injured players who do take the field are usually playing with reduced ability, which is why AGL is based not strictly on whether the player was active for the game or not, but instead is based on the player's game status that week (IR/PUP, out, doubtful, questionable, or probable).

Based on AGL, the Seahawks were the fifth-healthiest team in the NFL last season. They are one of only two teams (the Cincinnati Bengals) to finish in the top five in terms of AGL in each of the past two seasons.

In other words, their injury luck has actually been pretty good.

The outcome of next season will be partially based on whether they can avoid injuries at key spots. And if they can't, the Seahawks hope their depth will offer more solutions than it did in 2016.