Substitutes struggle to excel in first preseason game

NASHVILLE – Opening the preseason with a touchdown drive won’t ease the pain of how last season ended in the Super Bowl for the second-place 49ers.

But it was a beginning, literally, in the twilight of Tennessee.

With most of the regular starters out for Saturday night’s 17-13 loss to the Titans, the 49ers watched Brock Purdy’s backup Brandon Allen run an 11-play opening drive that culminated in a touchdown run by Jordan Mason, Christian McCaffrey’s backup.

Quarterback Josh Dobbs, in his 49ers debut, also produced a touchdown by being thrown across the goal line on a scramble, and attempted to engineer a game-winning touchdown drive in the final seconds before a Hail Mary was intercepted to end the game.

In between those offensive highlights, a lot went wrong, from coverage issues on special teams to poor angles on defense to a broken forearm suffered by cornerback Ambry Thomas.

Still, the live game action provided clues about which reserves have an edge at roster spots. Coach Kyle Shanahan also ceded play-calling duties for the first time to Klay Kubiak, a fourth-year assistant and his passing game specialist who worked from the coaches’ booth.

“It’s not a big deal. He’s ready for it and he’s earned it,” Shanahan said. “It was one of the more boring things for me personally, my first game in 16 years without calling plays. I had to throw up a red flag and call a couple of timeouts.”

Shanahan said he will likely resume play-calling duties next Sunday when the 49ers host the Saints, who will first host the 49ers in joint practices at UC Irvine on Thursday and Friday.

In total, the game was the first of any kind for the 49ers in six months, since their overtime loss in the Super Bowl to the Kansas City Chiefs.

This display also provided an escape from this summer’s soap opera about Brandon Aiyuk’s contract impasse and potential trade. The disgruntled 49ers wide receiver didn’t make the trip, nor did left tackle Trent Williams, whose continued misconduct cost him a $1.1 million fine for missing this game as well as $650,000 for missing the first 13 practices; those fines cannot be waived or reduced, according to the NFL’s collective bargaining agreement.

Shanahan had no update on either, saying of Aiyuk: “I’ve met with Brandon several times since we started camp. I’m not going to talk about anything personal. I feel the same way I did last week. I’m hopeful and I think it’s possible. Everything is open.”

Among those remaining in the Bay Area to rehab and/or rest: defensive end Nick Bosa, running back Christian McCaffrey (calf), linebacker Fred Warner (foot) and wide receiver Ricky Pearsall (shoulder).

Among the spectators wearing 49ers jerseys on the sideline were Purdy, Deebo Samuel, George Kittle, Kyle Juszczyk, Charvarius Ward, Deommodore Lenoir, DeVondre Campbell, Maliek Collins and Leonard Floyd. Kittle hosted a handful of players for workouts and lunch at his home in suburban Nashville, Juszczyk said on the CBS-5 San Francisco broadcast.

Allen impressed in his first action since last preseason as he looks to move from No. 3 option to Purdy’s immediate backup. The opening drive included completions to Ronnie Bell, Chris Conley and tight end Eric Saubert. Allen later threw pinpoint 40-yard passes, but those slipped through the hands of Tay Martin and Bell.

Allen’s longest and best pass came from his own end zone, converting a third-and-nine pass to Frank Darby for a 33-yard gain. Allen finished 7-of-13 for 98 yards, and was sacked on his final play against a Titans offense.

Dobbs took over in the second half, inheriting a 14-7 halftime deficit. Dobbs’ 6-yard touchdown run pulled the 49ers within 17-13 with 8:26 remaining, capping a 70-yard drive that included 21-yard gains by Trent Taylor on both a reception and a run.

Meanwhile, Purdy stayed involved, albeit from a distance. He listened to plays on a radio headset, reviewed video replays on a tablet, chatted with inactive star teammate Samuel and applauded a military man on the Nissan Stadium video board.

The only 49ers starters in this game who are likely to reprise their roles in the Sept. 9 regular-season opener against the Jets were safety Ji’Ayir Brown, right tackle Colton McKivitz and guards Aaron Banks and Dominick Puni, the latter of whom made his pro debut as a third-round pick.

The 49ers’ special teams coverage struggled early, allowing a 63-yard kickoff return in its debut under the NFL’s new format, then allowing a 26-yard punt return. Tackles by Jalen Graham and backup punter Pressley Harvin kept those returns from getting any worse. Each return set up a Titans touchdown drive, the first of which covered just 15 yards and ended with a 1-yard run by quarterback Will Levis.

Linebacker Dee Winters hit Levis on the previous play to prevent a score, but a holding penalty on Ambry Thomas negated that play to set up the first down and goal. The Titans were on the verge of their third touchdown in as many series until rookie safety Malik Mustapha made the defense’s first big stop, stopping a fourth-and-1 run for no gain at the 49ers 2-yard line.

Other notes:

— Mason used his lone series to show why he could dethrone Elijah Mitchell this season as McCaffrey’s primary backup. Mason had a 13-yard gain on the 49ers’ first drive. He had one pass slip through his fingers before finishing that drive with a 4-yard touchdown run. He had six carries for 34 yards.

— Taylor and Bell were again the 49ers’ first punters in the NFL’s new format, with Taylor’s first return of 18 yards going to the 26-yard line. Taylor’s next return was 18 yards to the 28-yard line. Just like in their last game (overtime in Super Bowl LVIII), the 49ers won the coin toss and received.

— Conley caught both of his passes for 30 yards, broke up the pregame huddle and was one of the 49ers’ captains, along with George Odum and Kevin Givens. Conley finished last season strong and excelled in the Super Bowl.

— Rookie Renardo Green started at cornerback (along with Rock Ya-Sin), played some inside play as a nickel back and recovered a fumble in the third quarter.

— Undrafted rookie Cody Schrader’s first NFL carries were minus-2, 6, 1, 1 and 0 yards.

— Matt Breida had no rushing yards on six carries and lost a fumble that Dobbs recovered.

— Kalia Davis was credited with the 49ers’ first sack, a fourth-quarter tackle on Malik Willis as he fled the pocket.

— Left tackle Chris Hubbard and center Nick Zakelj rounded out the starting offensive line. On the second series, Ben Bartch replaced Banks and Brandon Parker replaced McKivitz.

— The 49ers coaching staff was penalized for sideline interference on the Titans’ first kick return, setting up Tennessee’s first possession at the 49ers 15-yard line.