Questions still surrounding Bills receiver Percy Harvin

WATFORD, England (AP) — Percy Harvin is a question mark that no one seems to be able to answer.

The Buffalo Bills receiver, who sat out last week's game with a hip injury, did not travel to London with the rest of the team for what coach Rex Ryan has said was for personal reasons. Bills general manager Doug Whaley didn't have much more insight into the situation on Friday.

"Still just a personal reason that he's out and we'll address it as soon as we get some more answers on him," Whaley said at the team's practice facility north of London. "There's a lot of other things that are going on, it's just not strictly injury related."

The Bills (3-3) have been severely hampered by injuries, including to defensive tackle Kyle Williams and quarterback Tyrod Taylor. Ryan said Thursday that backup quarterback EJ Manuel will start Sunday at Wembley Stadium against the Jacksonville Jaguars (1-5).

Whaley said the team was adjusting to all the injuries, and defended his decision to let quarterback Matt Cassel go to Dallas.

"Arguably, you could say he's got a bigger upside," Whaley said about Manuel, who is in his third year in the league.

Taylor practiced on Wednesday, but sat out Thursday because his left knee was still sore. With the Bills having a bye next week, like all teams get after playing in London, Taylor will have an extra week off to heal.

"We believe that Tyrod will be able to play after the bye," Whaley said, then turning to the situation for Sunday. "When you got a backup, everybody believes that they have to raise their level of play up. EJ has to raise his level of play up.

"You got to get a level of consistency."

That is something Manuel and Bills have been struggling to attain. They have lost three straight home games, including a 34-21 setback against the Cincinnati Bengals last week with Manuel taking the snaps.

On Friday, Ryan said Manuel was a different type of quarterback than Taylor but was doing a "terrific" job.

"He doesn't have that kind of speed or elusiveness, but we can still do the same things schematically with either quarterback," Ryan said.

Besides the problems with the ball, the Bills defense has also been struggling and has so far failed to play up to its high-priced expectations. And the injury to Williams is a big problem for a team already missing starting safety Aaron Williams, who is out until at least December because of a neck injury.

Others who are injured and won't play Sunday include running back Karlos Williams (concussion), tackle Seantrel Henderson (concussion) and wide receiver Sammy Watkins (ankle).

"We got a lot of good football players not playing this week," Ryan said. "It's no excuse. We got to find a way, scratch, claw, do whatever it takes to get a win."

Buffalo has missed the playoffs for 15 consecutive seasons — the NFL's longest active playoff drought. And over that stretch, they've had just two winning seasons, 9-7 finishes in 2004 and 2014.

The injuries aren't making things any easier this year.

"Our expectations aren't going to dip," Whaley said, "but it is a challenge."