The Chargers' Gus Bradley-led defense will face some new challenges from their AFC West opponents this upcoming season. Let's take a look at the notable names on offense who have joined the division:

Kansas City Chiefs: The Chiefs added more firepower to an offense that ranked fifth in the NFL last season. Wide receiver Sammy Watkins was signed in free agency to give second-year quarterback Patrick Mahomes yet another weapon to go with the trio of Pro Bowlers currently at his disposal: tight end Travis Kelce, wide receiver Tyreek Hill and running back Kareem Hunt.

After three seasons with the Buffalo Bills, Watkins caught 39 balls for 593 yards and eight touchdowns last year as a member of the Los Angeles Rams. He's caught a 60-plus yard touchdown in each of his four NFL seasons with a career average of 15.9 yards per reception; numbers that, on paper, mesh with the strong-armed Mahomes.

Watkins is the brother of current Chargers defensive back, Jaylen Watkins.

Denver Broncos: The Broncos believe they found their fix at quarterback in Case Keenum. Outside of veteran wide receivers Demaryius Thomas and Emmanuel Sanders, Keenum's supporting cast is largely made up of several young faces who are also new to the team.

Denver made a concerted effort to add more playmakers to the roster through the draft. Rookie wide receivers Courtland Sutton (second round, Southern Methodist) and DaeSean Hamilton (fourth round, Penn State) are expected to be immediate contributors in 2018. The Broncos also drafted running back Royce Freeman in the third round. Freeman, Oregon's all-time rushing and touchdowns leader, will likely compete with Devontae Booker for carries in the Broncos' backfield.

A forgotten storyline out of Denver is the return of tight end Jake Butt. The Michigan standout missed the 2017 season recovering from an ACL injury suffered in his last college game. Meanwhile, former Broncos tight end Virgil Green signed with the Chargers in free agency.

Oakland Raiders: Head coach Jon Gruden has brought in a few household names this offseason to help out his young quarterback, Derek Carr.

After the Raiders released wide receiver Michael Crabtree in March, they quickly moved to replace him with Jordy Nelson. Nelson, 33, spent nine seasons in Green Bay with Aaron Rodgers as his quarterback -- and he has the numbers to prove it.

Nelson has 7,848 receiving yards and 69 touchdowns in his career. With Rodgers out for over half of last season with injury, Nelson posted just 482 receiving yards -- his lowest output since 2009.

The Raiders weren't done bolstering the position after signing Nelson. They traded a 2018 third-round draft pick for former Pittsburgh Steelers wide receiver Martavis Bryant, and also acquired Ryan Switzer from the Dallas Cowboys in exchange for defensive lineman Jihad Ward.

Running back Doug Martin was also signed this offseason after six seasons with the Tampa Bay Buccaneers. The 29-year-old has rushed for over 1,400 yards twice in his career, most recently in 2015. He'll join a backfield led by Marshawn Lynch, 32.