Thearon W. Henderson / Contributor

The first half of the 49ers’ season leaves us with more roster questions than answers. Even though the team is young — it entered 2018 as the NFL’s tenth-youngest squad — several promising second-year players have endured slumps, while experienced players have either regressed or plateaued.

Midway through the season, the 49ers (1-7) are already on the brink of playoff elimination. No one expects them to win out, but the second half of the season is important for reasons beyond results, with a handful of players entering a pivotal stretch that will play a part in their future with the 49ers.

We broke down, in order, which players have the most at stake in the final eight games of the 2018 season.

Ahkello Witherspoon

Witherspoon is one of the second-year defensive players who have disappointed. He was supposed to take the next step from promising, late-blooming rookie last year to a legitimate presence opposite Richard Sherman this year.

That has not happened. Witherspoon has been exposed, benched, and exposed some more. The worst of it came in Week 2. The Detroit Lions exclusively targeted Witherspoon’s side, to which they had success. He was subbed out for Jimmie Ward for a possession before re-entering the game. Witherspoon has slowly improved throughout recent weeks, but he is still allowing touchdowns with each passing week.

We aren’t hitting the panic button on Witherspoon. He is 23 years old. But he has been a liability, with the 49ers surrendering 235.2 passing yards per game, despite allowing just 142 total yards when targeting Sherman. Most of the damage has been done on the defense’s right side.

Witherspoon will have to rebound if he expects to retain his starting job in 2019 and beyond. Rookie Tarvarius Moore is waiting for his opportunity. With the 49ers waiving Greg Mabin Tuesday, and Jimmie Ward potentially gone after the season, it’s likely the 49ers will draft another cornerback in 2019 to compete.

Cassius Marsh

Marsh has been San Francisco’s featured LEO throughout the season. His statistics hardly back it up. In 279 snaps, Marsh has just one sack, one fumble recovery, 10 solo tackles, and four for a loss on the year. Pro Football Focus ranks Marsh as the sixth-worst edge defender out of all starters.

Ronald Blair, comparatively, has played 34 fewer snaps and produced 2.5 sacks, 11 solo tackles, and five for a loss. These aren’t sterling numbers, but they’re better than Marsh’s.

The 49ers did not draft an edge rusher in April largely because they believed in Marsh. They signed Jeremiah Attaochu, but he was released prior to Week 1. Marsh has had plenty of opportunity, but he disappears for long stretches, generally does not finish pass rushes, and struggles to set the edge on rushing downs.

The upcoming draft class is loaded with marquee edge rushers. The 49ers are likely to have access to some of them with a top pick awaiting. Marsh, who is under contract through 2019, will have to improve in the second half of this season to secure a similar role next year.

Solomon Thomas

Witherspoon is placed higher on this list than Thomas because the second-year cornerback has disappointed despite fitting Robert Saleh’s scheme. You could argue Thomas does not. Former 49ers safety Donte Whitner feels Thomas is better suited for a 3-4 defense. Thomas was dominant on the interior at Stanford, winning the Pac-12 Defensive Player of the Year award in his final college season.

Either way, Thomas has not produced as you’d expect out of the No. 3 overall pick in the 2017 NFL Draft. Thomas has just three sacks and 14 quarterback hits in 24 career games. The 49ers have recently deployed Thomas more on the inside, where he has played better.

But at what point is his production going to resemble that of a top-three draft pick?

Pierre Garcon

Garcon was subjected to trade talks as Tuesday’s 1 p.m. deadline approached. ESPN’s Adam Schefter reported “at least three teams” inquired about Garcon. Ultimately, the 49ers did not bite.

It’s possible they will not pick up the final three years of his five-year contract after the 2018 season, however.

There are a few variables at work in regards to Garcon’s future. The first, and most obvious: Garcon looks a step or two slower than in the past. The 32-year-old has just 21 catches on 40 targets for 231 yards in seven games this season. Last year, his first with the 49ers, he was on pace for 80 catches and 1,000 yards, but he suffered a season-ending neck injury in Week 9.

Kendrick Bourne, Garcon’s backup, played well in his first extended action of his two-year career. Bourne caught seven passes for 71 yards, more than any of Garcon’s seven outings in 2018.

Garcon, who missed Week 8 with shoulder and knee injuries, will have to prove he can stay healthy and produce at a high enough level for the 49ers to pay him the $6 million he is owed next year and $24.5 million over the next three. If Bourne continues to play well, the 49ers may choose the cheaper route.

Laken Tomlinson

Tomlinson is playing in a contract year. The 49ers chose not to pick up his fifth-year option back in May, making him a free agent after the 2018 season concludes. General manager John Lynch said he wants to re-sign Tomlinson, but Lynch chose not to pick up the fifth-year option because of the inflated price at guard.

Tomlinson has flashed his first-round talent this year. The left guard ranks as Pro Football Focus’ No. 27 overall interior offensive lineman.

It seems the 49ers have found their offensive line of the foreseeable future, with center Weston Richburg, right guard Mike Person, and rookie right tackle Mike McGlinchey elevating the unit’s performance in their first years starting on the Joe Staley-led unit. Tomlinson fits right in. If he continues his solid play, expect the 49ers to reward him with a new contract prior to the 2019 season.

Jimmie Ward

The 49ers picked up the fifth-year option in Ward’s rookie deal, making him a free agent at season’s end. The hybrid defensive back is San Francisco’s highest-paid player in 2018.

Ward, who entered the season as the backup at every secondary position aside from strong safety, has had a role with Witherspoon’s struggles and Adrian Colbert’s high ankle sprain that sent him to injured reserve last week. The idea of retaining someone like Ward, who can play all five secondary positions, is a major luxury.

“I think he’s an unbelievable corner and an unbelievable free safety,” Saleh said Wednesday. “When I say it, I really mean it. He’s one of the best 11 football players on this team on defense.

But Ward has only been slightly better than Witherspoon, falling victim to the issues riddling the entire secondary: lack of playmaking and blown coverages. Sherman is the only 49ers defensive back who has consistently played well this year. Ward faces an important eight final games, which may be his final in a 49ers uniform.

Jaquiski Tartt

Tartt does not have to worry about financial security. In May, the 49ers extended the strong safety’s contract through 2020.

Tartt and Colbert have been regarded as San Francisco’s safety duo of the future. But neither player has noticeably progressed this season. Colbert will likely spend the remainder of the season on injured reserve.

Tartt has battled a nagging shoulder injury. He will miss his third game of the season Thursday night with the injury. He has not been active for a full 16-game schedule throughout his four professional seasons.

When Tartt has been on the field this season, he has been mediocre. It’s clear he excels in run-stop situations, where he ranks 13th out of all NFL safeties, a necessary trait at his position in Saleh’s Cover-3 scheme. But Tartt has struggled in pass coverage. He dropped an easy interception in Week 7, though he caught one in Week 8, which was San Francisco’s first forced turnover since Week 4.

There has not been much of a drop-off between Tartt and backup Antone Exum, who will miss Week 9 with a concussion, this year. The secondary has forced just two interceptions, the second-fewest in the league.

Tartt is part of San Francisco’s plans moving forward, but his health and lack of progression are worrisome.

Arik Armstead

Like Thomas, Armstead is another first-round pick who has not lived up to expectations. He has produced just three sacks, 22 solo tackles, and five for a loss. But he grades as Pro Football Focus’ fifth-best interior edge defender in run-stop situations.

Prior to the season, the 49ers picked up Armstead’s fifth-year option for 2019. He has the potential to sign an extension should he stay healthy and assert himself more in the passing game. Those are big questions.

Richard Sherman

Sherman’s status as a defensive cornerstone will not change in the second half of the season. But he has plenty at stake in regards to cashing out his incentive-laden contract.

Sherman earns a $1 million bonus if he makes the Pro Bowl and a $2 million bonus if he is named to the Associated Press All-Pro team. If Sherman makes the 2018 Pro Bowl, his 2019 contract becomes fully guaranteed as of the third day of the league year, according to Pro Football Talk. Sherman has more-than-likely missed out on the $1 million bonus he would have made had he played in 90 percent of snaps this year. He has already missed two games, and his status for Week 8 is in question.

The 49ers filled Sherman’s contract with incentives to ensure he returned to form following an Achilles tear he suffered last November. Sherman has been as good as advertised, allowing just seven completions on 19 targets this year, according to Pro Football Focus.

He will need to maintain that production, while staying healthy, to maximize his contract.

C.J. Beathard

The verdict is still not out on Beathard as an NFL quarterback. Every encouraging performance follows a disappointing one. Barring a serious injury, he will likely remain the starting quarterback for the remainder of 2018. By season’s end, we should have a better feel for his ability to play in the NFL.

Kyle Shanahan has long maintained that Beathard gives the 49ers the best chance to win with franchise quarterback Jimmy Garoppolo injured. The 49ers would like to see it Beathard close the season strong should he have to command the offense again beyond 2018.