SANTA CLARA, Calif. (AP) -- A big part of the San Francisco 49ers' offense the past few seasons will be playing against them Sunday for the Tennessee Titans.
But an emerging San Francisco attack appears to be absorbing the loss of Delanie Walker well at the tight end position, and it's not just the exploits of starter Vernon Davis.
Rookie Vance McDonald has played well as the new No. 2 to Davis and veteran Garrett Celek also has contributed in an offense that uses two tight-end formations often, just like it did when the versatile Walker was lining up at multiple positions the past two years for offensive coordinator Greg Roman.
Having extra tight ends on the field has helped get San Francisco's run game going, and last week's career-best performance by Davis helped spark a lagging passing attack that ranks just 30th in the NFL.
Davis had eight catches for a career-high 180 yards receiving and two touchdowns in San Francisco's 32-20 victory over the Arizona Cardinals, but he said those numbers aren't important.
It's the body of work he and the team's other tight ends are doing to help the 49ers win and get the offense out of an early season funk that are important. San Francisco is looking for more of that Sunday when the 49ers (4-2) travel to Tennessee to play the Titans (3-3), whose new starting tight end served as Davis' backup the past seven seasons in San Francisco.
''I'm past the point that I only get excited about catching passes and getting yards and scoring touchdowns,'' Davis said Friday. ''That's not what I'm here for. I'm here to help this team in any phases that I can, and that's what all our tight ends are doing. Delanie did a lot of great things for us on the field, made a lot of plays. But I don't feel like it's really a loss, because when the new guys come in, they fill that void.''
McDonald, San Francisco's second-round draft pick this year, is averaging 13.2 yards per catch as a receiving complement to Davis at the position. But it's his improved blocking that really has made an impression in recent weeks, and that's had an impact on a rushing attack that has climbed to fourth in this week's NFL rankings.
After averaging 101.6 yards on the ground in their first three games, the 49ers have rushed for an average of 181.6 the past three weeks in victories over St. Louis, Houston and Arizona.
''Vance has performed a critical role for us here in these last three victories,'' Roman said. ''We've asked a lot of him the past three weeks and couldn't be more pleased with how he's done.''
The 49ers drafted McDonald essentially to take the place of Walker, who left the team during the offseason as a free agent to sign a four-year, $17.5 million deal with the Titans. San Francisco couldn't afford to pay that kind of money to a No. 2 tight end, and coach Jim Harbaugh said this is the week the Niners will most feel the effect of that decision.
''I'm not happy to see him in a Titans 82 jersey,'' Harbaugh said. ''On a personal level, I miss Delanie, and he's really playing well. Our challenge in defending him is high. But our tight ends are playing extremely well, led by Vernon Davis, who in our opinion is the best tight end in the National Football League.''
Like Davis and McDonald, Celek also has the versatility to help as both a receiver and a blocker. He had a 30-yard reception against Indianapolis in Week 3 and sees a lot of time when the Niners go to multiple-tight end sets.
That's something happening more often in recent weeks as the 49ers look to find a rhythm and hit their stride offensively.
''For the tight ends, there's a lot on our plate,'' Celek said, ''and I feel like it's increasing more and more. (McDonald) has definitely closed that gap that Delanie was. I think we've done a really good job up to this point, and we just keep getting better and better.''
NOTES: WR Michael Crabtree, who tore his Achilles tendon in May, was on the field running passing routes this week and is expected to return to practice soon. Crabtree declined an interview request Friday, but he expects to return to game action sometime in November. ''I'm just working bro, and I'm grinding extra hard,'' Crabtree said.