Which areas are most impacted by having Vaitai in Peters' place?

Officially, the Eagles aren't worried about having Halapoulivaati Vaitai replace franchise legend Jason Peters at left tackle, on  Sunday against San Francisco and presumably for the remainder of the season. Doug Pederson confirmed Friday that Vaitai will step in, as previously reported, with Lane Johnson staying at right tackle.

Unofficially, it's complicated. Teammates and coaches do seem to believe that  Vaitai, a 6-6, 320-pound fifth-round pick in  2016, is ready to play and lacks only experience to become a solid,  reliable tackle. But Peters was so much more than that.

The Eagles have run the ball around left end 53 times this season, the most of any team in the NFL, taking advantage of Peters' incredible power and agility. Can they still do that?

And if Vaitai, embarking on just his 15^th NFL game, his eighth start, needs chip-blocking help, will that affect the stellar season tight end Zach Ertz is having as a pass-catcher (team-high 39 catches for 494 yards and five touchdowns)?

When Johnson left for a 10-game league suspension last season, the Eagles weren't as deep; Vaitai hadn't played an NFL snap before stepping in for Johnson at Washington last Oct. 16. Johnson's absence eventually affected pretty much everything, including then-rookie quarterback Carson Wentz, who fell into some bad habits as his protection crumbled. The Eagles went 2-8 during that span.

So, in the long run, an awful lot is at stake here, even if the 6-1 Eagles are heavy favorites this week against the 0-7 49ers.

"I'm going to do my best and play for J.P.," Vaitai said Friday. "No one can replace J.P., but I've got the opportunity, so I'm going to play for him. … The coaches will call what they want. If they call 'left,' I'm going to do my job, if they call 'right' I'm going to do my job."

Vaitai said he spoke with Peters on Tuesday, the day after the nine-time Pro Bowl tackle tore his right ACL and MCL, when Washington defensive lineman Ziggy Hood fell across the back of his legs.

"He said,  'Just go out there and have fun, be loose, just play like practice. Don't hesitate – if you hesitate, you're beat,' " Vaitai said.

"For me, don't overset. That's the No. 1thing for me right now. … I need to focus [better than when he went in for Peters against Washington]."

Will he have help very often?

"We'll see," Vaitai said. "If not, I'm going to be doing my job. The rest of the season, I'm going to be playing for Jason Peters. I'm going to make him proud."

Pederson said that he, offensive coordinator Frank Reich, and offensive line coach Jeff Stoutland discussed "what's best for that group and for us offensively."

Though Johnson has been penciled in as Peters' eventual successor since Johnson was drafted fourth overall in 2013, Johnson has said he'd rather not make the transition in midseason, and has pointed out that the Eagles' right side will face several dominant pass rushers down the stretch.

"Really, right now Lane is playing extremely well on the right side," Pederson said. "Didn't want to disrupt two positions. So it made sense to keep 'V' over on the left side."

Pederson said that preparing for next season, and the possibility Peters won't be able to return at age 36, "hasn't even crossed my mind yet."

Losing Peters brings even more focus to something that has been a minor trouble spot ever since Darren Sproles was lost for the season last month against the Giants – blitz pickup from the running backs. The Eagles were reported to have tried to sign Blake Jarwin, a hybrid tight end/fullback-type, off Dallas's practice squad this week. The Cowboys promoted Jarwin to their roster to keep him.

"This week, I think we're going to do a better job of chipping off the edge, making sure our tackles are more secure with their blocking," rookie running back Corey Clement said.

Clement said the toughest part of blitz pickup isn't the actual blocking but "identifying who is who, and who is being left for me, as a running back."

Center Jason Kelce calls out information that helps Clement make that calculation.

Second-year running back Wendell Smallwood agreed with Clement's assessment.

"The physical part, I think that's last," he said. "I think getting yourself in the right position and knowing where to go and not having the mental errors is the hard part. A lot of it's film study, but also a lot of it is getting the communication with the line and the quarterback and the running backs and the receivers."

Smallwood said the game plan hasn't changed this week, with the switch from Peters to Vaitai.

"We know 'Big V' can step up; this isn't his first go-round," Smallwood said.

Smallwood, the team's most trusted pass-blocking back after Sproles, missed the Arizona and Carolina games with a knee injury. Carolina definitely tried to exploit that situation with blitzing.

"The Carolina game, we thought Carson took a lot of hits. This league, if they think you have a weak spot, they're going to try to expose it," Smallwood said. "We're ready for it, for the rest of the year."