LONDON — Days after his job appeared to be in jeopardy, Ryan Tannehill turned in a stellar performance and the Miami Dolphins dismantled the Oakland Raiders in emphatic fashion at Wembley Stadium on Sunday.

There could be serious repercussions for the Raiders, who head home for the first time in 10 days with an injured quarterback and head coach rumored to be on the way out as Oakland begins its bye week.

Dolphins cornerback Cortland Finnegan erased any faint hopes of a second-half rally with a 50-yard fumble return, scooping up a shotgun snap that never made it to the quarterback, for a touchdown to push Miami ahead 38-7 with 3:59 left in the third quarter. That came one play after backup Matt McGloin entered the game for rookie quarterback Derek Carr, who injured his knee and ankle on an incomplete pass.

The Raiders marched 74 yards on their opening drive to jump ahead 7-0 on a 3-yard toss from Carr to tight end Brian Leonardt, but Oakland played the role of bystanders for much of the rest of the game.

It didn’t take Tannehill, who passed for 204 yards and two touchdowns in the first half alone, and the Dolphins much time to expose Oakland’s defense, scoring on its first four drives before half. Nine of Miami’s first 20 plays went for at least nine yards, including three second-quarter touchdowns: 13 yards from Tannehill on a short screen pass to Mike Wallace, a 9-yard scamper by Lamar Miller on the ensuing possess that staked Miami to a 17-7 lead and an 18-yard reception by Dion Sims with 1:53 to go in the second quarter.

Tannehill finished the game 23 of 31 for 278 yards.

The Dolphins intercepted McGloin twice, Carr once and defensive end Derrick Shelby had two sacks.

Trailing 38-7, McGloin zipped a 22-yard touchdown pass to Andre Holmes midway through the fourth quarter.

The Raiders entered the game ranked last in the NFL in total offense and sputtered through the game with short drives dominated by checkdown passes and modest running gains. Oakland has 23 points in its last eight quarters. After flying from New York to England immediately after the Week 3 loss to the Giants, head coach Dennis Allen and his team limps back to Oakland for a bye week as speculation mounts about Allen’s future.

Tannehill was nearly unstoppable in the first half, coming within three completions of Chad Pennington’s consecutive completions mark with 17. Including the Wallace score, Tannehill was perfect on the first TD drive (6-6, 86 yards) and 17 of 19 in the opening half with a 146.5 passer rating.

Caleb Sturgis made a 41-yard field goal to get the Dolphins on the board in the first quarter.

NOTES: The game at Wembley Stadium is the first of three scheduled as part of the NFL International Series this season. The Dolphins played in the first ever regular-season game in London in 2007. Miami lost that game to the Giants, 13-10. … Raiders RB Darren McFadden starting at running back and had his longest gain of the season (12 yards). … The Raiders last won a regular-season game on Nov. 17, 2013. … Oakland is 8-28 since the start of the 2012 season. … The Dolphins last scored 38 points in 2009 (Oct. 4 vs. Buffalo).