The last time the Seahawks took to the turf at CenturyLink Field, they were celebrating their still-fresh Super Bowl win, the stadium serving as the conclusion to a parade that will live forever in Seattle sports history.

Friday night, they’ll return to the Clink to continue the process of building what they hope is another Super Bowl winner, hosting the San Diego Chargers in their second exhibition game. Kickoff is 7 p.m.

The Seahawks will, of course, hope to get a victory after seeing their nine-game exhibition winning streak snapped last Thursday at Denver, 21-16.

But this being the preseason, of more importance is gauging the progress of players and position groups.

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Here are six key areas to watch Friday night:

1. The offensive line. In the words of offensive line coach Tom Cable, the play of the line at Denver “was really average.’’ Seattle allowed three sacks and its quarterbacks, all known for their mobility, were on the run.

Simply getting healthy should make for a better performance this week. Left guard James Carpenter and center Max Unger — each of whom practiced regularly this week — are expected to play. Left tackle Russell Okung, who also returned to practice, might still be a week away.

Having the first unit work regularly together in practice this week was a big step in the line returning to form.

One spot still up in the air is right tackle. Rookie Justin Britt remains atop the depth chart after what coaches said was a solid performance at Denver. But veteran Eric Winston will also get plenty of playing time against the Chargers.

2. The second-unit defense. Coach Pete Carroll was candid in his assessment of the play of the reserve defense against Denver, saying “we played poorly at the line of scrimmage last week and I was really disappointed that we looked like that. … We got blocked.’’

Seattle’s reserves typically dominate in the preseason. Seattle went 4-0 in each of the past two preseasons, outscoring opponents a combined 51-17 in the second half in 2012 and 74-20 in 2013.

Thursday at Denver, though, the Seahawks were outscored 14-6 in the second half. “I’m hoping that the line of scrimmage will start the chain reaction that we will play better when it comes to second-half ball,’’ Carroll said.

3. Tharold Simon. The second-year cornerback was thrown out of last week’s game early in the third quarter, playing just 15 snaps. Simon has been one of the rising stars through the early stages of training camp, appearing to have secured a spot as a backup corner. But the team needs to see him play on the field after he missed all of last season with a foot injury.

“This preseason is really important for him,’’ Carroll said. “He’ll play a ton these next three weeks and we’ll try to take him through it and grow with him with a really positive outlook that he can be a big factor.’’

4. Earl Thomas as a punt returner. Thomas will again get first crack at returning punts as the Seahawks search for a replacement for Golden Tate. But others will also get a shot (Richard Sherman and Paul Richardson are listed as backups on the depth chart and Bryan Walters also is in the mix). Thomas had one return at Denver, for no yards.

5. Backup quarterbacks. While Tarvaris Jackson is listed second on the team’s depth chart, coaches maintain that his battle with Terrelle Pryor for the backup spot behind Russell Wilson remains wide open. The two often alternate working with the second and third units, and it wouldn’t be a surprise to see Pryor get the first call after Wilson on Friday (Seattle alternated the order of its backup QBs by game last year, as well). “We’re really trying to give them an equal shot to see where they fit in the competition of it,’’ Carroll said.

6. O’Brien Schofield/Benson Mayowa. The two are locked in a battle as one of the pass rushers in the nickel defense. Mayowa went with the first-unit nickel last week, but Schofield is expected to get that chance this week.

Note

• Rookie defensive tackle Cassius Marsh could play after practicing on Thursday. He left Wednesday’s practice after injuring his knee, but an MRI showed no significant damage.

Bob Condotta: 206-515-5699 or bcondotta@seattletimes.com. On Twitter @bcondotta