What happened: Seattle lost Boye Mafe but returns Rylie Mills alongside Byron Murphy II and Leonard Williams. Los Angeles pairs Myles Garrett with Kobie Turner, Braden Fiske, Poona Ford and Byron Young.
Why it matters: San Francisco returns Nick Bosa and Mykel Williams while adding Osa Odighizuwa and third-round pick Romello Height. Arizona added Jonah Williams and retained L.J. Collier as each contender reworked its pass rush.
By the numbers: Seattle and Los Angeles each recorded 47 sacks last season, followed by Arizona with 30 and San Francisco with 20. Seattle's total was distributed among 17 players.
What to watch: Preseason rotations will offer the first look at how the rebuilt fronts divide pass-rush snaps. The regular-season race begins in September.