The Seattle Seahawks begin their three-day rookie minicamp Friday, and much of the focus will be on new faces on the defensive side of the ball.

Four of the team's first five draft picks -- and six overall -- were used on defensive players, including four defensive backs.

Last year was the first time in five seasons that Seattle failed to lead the league in fewest points allowed. Earl Thomas missing five games was a huge blow, and yet the Seahawks still finished fifth in defensive efficiency, a ranking most teams in the NFL would be thrilled with.

But the job of NFL coaches and general managers is to get ahead of potential problems. And that's exactly what the Seahawks are doing. GM John Schneider said last month that one of the reasons why the Seahawks considered dealing Richard Sherman this offseason was to get younger on defense. While that was not the primary reason, it's a theme that fits with what Seattle did in the draft.

Football Outsiders uses a metric called snap-weighted age (SWA) to determine how old teams are on each side of the ball and at different position groups. Rather than measuring age by the entire roster, it adjusts for starters, backups and rotational players.

Per SWA, the Seahawks had the seventh-oldest defense in the NFL last season. Seattle's defensive backfield was seventh-oldest, and its defensive line was eighth-oldest. It probably isn't a coincidence that the Seahawks spent six draft picks on those two areas of the roster.

Offensively, the Seahawks were the fourth-youngest group in the NFL last season. In the coming weeks, Pete Carroll will mention often how young Seattle was up front in 2016. Schneider has admitted that the Seahawks probably got too young, too fast. According to SWA, the Seahawks had the second-youngest offensive line in the NFL last season.

The only positional group on offense that ranked older than league average was tight end (eighth-oldest).

The guess here is that the Seahawks' numbers won't look much different after 2017. The offensive line added some experience in Luke Joeckel but is still a young group. The defensive line added Malik McDowell and Nazair Jones while getting rid of veteran Tony McDaniel. But Michael Bennett and Cliff Avril (both 31) are still the unit's best two players and will be tough to get off the field.

The secondary is still led by Sherman (29), Kam Chancellor (29) and Thomas (28).

But it's never about looking just one season ahead. Chancellor and Jimmy Graham (30) are two of the team's key free agents next offseason. And given the trade talks this offseason, it's fair to wonder whether Sherman will return in 2018.

Rookie minicamp will give the coaches their first look at Shaquill Griffin and Mike Tyson, two guys who have a chance to compete for immediate playing time at cornerback. McDowell will be out to prove that concerns about his motor were misguided.

Jones, Delano Hill and Tedric Thompson will look to make their mark as well.

Carroll said the draft wasn't about replacing the Legion of Boom, and if we're talking about 2017, that's accurate. But the Seahawks have certainly given themselves more options to get younger on defense than they had a year ago.