49ers’ Nick Bellore faces a daunting task

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With the Jets’ final pick in the 2011 draft, general manager Mike Tannenbaum and many of their coaches wanted to select Central Michigan inside linebacker Nick Bellore.

The problem: Head coach Rex Ryan, per tradition, was allowed to make their final pick and he selected Colorado wide receiver Scotty McKnight as a favor to quarterback Mark Sanchez, who grew up with McKnight.

Ryan, who later called Bellore to offer him a free-agent contract he accepted, explained the Jets hadn’t drafted him because “you’re not the quarterback’s best friend!”

Bellore’s unique NFL start was chronicled in “Collision Low Crossers,” written by Nicholas Dawidoff, who was given tremendous access for his book on the 2011 Jets. And, given Bellore’s presence throughout the book, the 496-page tome might represent the most attention he has received during a decidedly low-profile career.

Until now, that is.

The spotlight will be squarely on Bellore on Thursday night when the 49ers host Arizona in their first game this season without inside linebacker NaVorro Bowman, who sustained a season-ending Achilles tendon tear Sunday.

Bowman was a first-team All-Pro in each of his four full seasons as a starter. Bellore? He has been a core special-teams player who had played 40 defensive snaps in his six-year career before replacing Bowman in the 24-17 loss to the Cowboys.

Nick Bellore did well this preseason — here sacking the Texans’ Tom Savage — but he’s seldom been used on defense in the regular season. Nick Bellore did well this preseason — here sacking the Texans’ Tom Savage — but he’s seldom been used on defense in the regular season. Photo: Connor Radnovich, The Chronicle Buy photo Photo: Connor Radnovich, The Chronicle Image 1 of / 1 Caption Close 49ers’ Nick Bellore faces a daunting task 1 / 1 Back to Gallery

The swap of the star for the special-teamer is a blow to a team that has allowed an average of 35.7 points and 458.3 yards during a three-game losing streak. For Bellore, however, it’s a chance to finally prove he’s capable of more than covering punts and kickoffs.

If he starts against Arizona, and he has said he expects to do so, it will mark his first start since Nov. 26, 2010, when Central Michigan lost at Toledo.

“Now that I’ve got my shot,” Bellore said, “I’ve just got to do what I know I can do.”

After being viewed as strictly a special-teams player, Bellore, 27, could be getting his chance because of defensive coordinator Jim O’Neil.

O’Neil, then an assistant defensive backs coach, was among those lobbying for Bellore in the Jets’ draft room in 2011. O’Neil was impressed by Bellore’s toughness and instincts based on their past meetings: He was an assistant coach at Eastern Michigan from 2006 through ’08 and had seen Bellore up-close in two Mid-American Conference games.

At Central Michigan, Bellore was a four-year starter and three-time All-MAC selection who ranked third in school history in tackles (472).

O’Neil and Bellore spent two seasons together with the Jets, before reuniting when O’Neil was hired by the 49ers in January.

“He’s got unbelievable football instincts,” O’Neil said. “I think that’s one of the things that makes him a great special-teams player because he’s got a way to sift through trash and make plays on ball carriers. And he does the same thing at inside backer.”

Bellore’s special-teams skills are unquestioned: He led his team in tackles in four of his first five seasons.

However, his inside-linebacker ability is unknown given his near-nonexistent playing time. In the preseason, he had six tackles, a sack, three quarterback hits, a pass breakup and a fumble recovery. Then, he had his first career interception in a nine-snap performance during a 37-18 loss at Seattle in Week 3.

However, he often easily was cleared out of running plays in a four-tackle, 29-snap performance Sunday that began when Bowman was injured with six minutes left in the third quarter. Rookie running back Ezekiel Elliott had 85 of his 138 rushing yards after Bowman’s exit.

“I obviously think I could have played better,” Bellore said. “There’s stuff I could clean up, a little rusty out there. I think it’s correctable stuff.”

Bellore probably will have plenty of chances to make corrections Thursday.

The Cardinals will be without quarterback Carson Palmer (concussion), and journeyman backup Drew Stanton could spend plenty of time handing the ball to running back David Johnson. The NFL’s leader in yards from scrimmage (505) will test a defense that’s allowing a league-worst 140.5 rushing yards a game and will be without rookie defensive tackle DeForest Buckner (foot), the No. 7 overall pick who also was injured Sunday.

Five years ago, after Bellore was bypassed in the draft, he was forced to wait three months to sign with the Jets because the 2011 draft took place during the lockout.

It foreshadowed an NFL career that has required plenty of patience. On Thursday, though, his long-awaited chance will arrive.

“I’ve always aspired to play defense,” Bellore said. “Obviously, I know that special teams has been my meal ticket in the NFL, but it’s never been out of my mind to be ready for any game.”

Eric Branch is a San Francisco Chronicle staff writer. Email: ebranch@sfchronicle.com Twitter: @Eric_Branch

Cardinals (1-3) at 49ers (1-3)

When: 5:25 p.m. Thursday

TV/Radio: Channel: 5 Channel: 13 Channel: 46 NFL Network/810, 107.7

Spotlight on: Nose tackle Mike Purcell: Even before the 49ers lost All-Pro linebacker NaVorro Bowman to a season-ending Achilles tendon tear Sunday, they were powerless to stop the run: They have allowed three straight 100-yard running backs in the same season for the first time since 2004 and rank last in the league in rushing yards allowed per game (140.5). Purcell has struggled to replace sturdy nose tackle Ian Williams and could cede snaps at some point to Glenn Dorsey, who is being brought back slowly from a torn ACL he suffered 11 months ago. With QB Carson Palmer sidelined, the Cardinals will see if RB David Johnson, who leads the NFL in yards from scrimmage (505), can become the latest 100-yard rusher against the 49ers.

Injuries: Cardinals — Palmer (concussion) is out. 49ers — DT DeForest Buckner (foot) and CB Jimmie Ward (quadriceps) are out; WR Jeremy Kerley (ankle), TE Vance McDonald (hip) and Dorsey (knee) are questionable.

Big 3

Arizona backup QB Drew Stanton, who will replace Palmer, ranks 73rd in completion percentage and 71st in passer rating among 76 QBs with 450-plus attempts since 2008.

The 49ers have allowed 23 rushing TDs in their past 19 games. They allowed 28 rushing TDs in 64 games from 2011 through ’14.

The 49ers are 7-18 in their past 25 games after posting a 45-18-1 record in their previous 64 games.

— Eric Branch

Concussion sidelines Arizona’s Palmer

Arizona quarterback Carson Palmer will not play against the 49ers on Thursday night because of a concussion he suffered Sunday. Drew Stanton will replace Palmer.

In 2014, Stanton, 32, threw for 244 yards and two touchdowns in a 23-14 win against the 49ers in one of the highlights of his eight-year career. Stanton does have a 7-5 record as a starter, but he also possesses a 54.0 career completion percentage and a passer rating of 66.5.

On Sunday, Stanton completed 4 of 11 passes for 37 yards and threw two interceptions after replacing Palmer in a 17-13 loss to the Rams that dropped the Cardinals to 1-3.

Arizona head coach Bruce Arians pointed to Stanton’s 5-3 record as a fill-in starter in 2014 during a conference call with the Bay Area media Tuesday.

“I thought he played extremely well,” Arians said. “We don’t change anything we do: He’s extremely knowledgeable in the offense, and I feel very comfortable with him in there.”

— Eric Branch