"Well, he's a veteran guy," Del Rio said Monday. "He's played a lot of good ball over the years and we're excited to have him. We're a little green at the linebacker position, so to add somebody with the experience that he has, we think it's a nice addition for us. We'll get him up to speed and see how quickly we can get him there and on the field."
After taking a walkthrough with the team Monday, Bowman wasn't ruling out playing Thursday. "If I'm prepared enough, I'll definitely try to give it a shot," he said. "Hey, I'm going to show you something."
Bowman signed a one-year, $3 million deal with the Raiders, sources told ESPN's Adam Schefter.
He said going to Oakland was an easy decision.
"Of course I didn't want to have to transition, make a big transition," he said. "I like the Bay Area and the Raiders have a good thing going. I feel like my presence could help them out."
Bowman fills a need for the Raiders at middle linebacker with rookie fifth-round draft pick Marquel Lee out with an ankle injury and the team using a pair of undrafted rookies in Nicholas Morrow, who played at Division III Greenville College last year, and Xavier Woodson-Luster, an Arkansas State product, in Lee's place.
Bowman brings "a lot of experience, a lot of leadership, a lot of physicality," two-time Pro Bowl outside linebacker Khalil Mack said. "You're talking about a guy that, all you've got to do is turn the ball back to him. He's going to be there. And that's what we're ready to do."
Outside linebackerBruce Irvin said he was glad to have another proven veteran on the team.
"Another dog. Another dog, man," Irvin said. "He knows a lot of football. Been around a lot of football and been in a good system so, like Khalil said, we've just got to do our job and turn (the ball carrier) back, and he'll be there...he's got the pedigree. He knows what a good defense consists of. He knows the blueprint on how to become one of the top defenses in the league so I'm just happy to have him with us."
Second-year linebacker Cory James said he was excited to have Bowman in Oakland.
I feel like it's going to help all of us,'' James said. I was just asking what time will he get in tomorrow so we can watch film. I feel it will help me out to learn from a future Hall of Famer. I'm just excited that he's here.''
Before cutting Bowman, the 49ers had agreed to trade the veteran to the New Orleans Saints for a seventh-round draft pick, league sources told ESPN. But after agreeing to the trade, the 49ers learned that Bowman preferred to be a free agent and decide where he would play next.
Bowman said he was looking forward to the fresh start.
"It's a refresher for me," he said. "It's a new picture, new scenery. Guys are a special group of guys. You can see the talent they have on the offensive side of the ball. I'm excited. I'm excited to play for an offense that's eager to score points and I look forward to it."
In his time with the 49ers, Bowman became one of four players in franchise history to earn four first-team All-Pro nods, and finished his time in Santa Clara with 709 total tackles, 12.5 sacks, seven forced fumbles and four interceptions.
Bowman also provided some of the most memorable moments in franchise history, including his 89-yard interception return for a touchdown that nailed down a playoff spot in 2013 and closed down Candlestick Park, and the pass breakup in the NFC Championship Game that sent the Niners to Super Bowl XLVII.
A devastating left knee injury suffered in the 2013 NFC title game kept him out for the entire 2014 season, and a left Achilles injury cost him the final 12 games of last season. Such injuries have slowed him of late as he has struggled to cover running backs.
Through the first five games of the season, Bowman had 38 tackles, but he'd also played 333 snaps, second most among linebackers.
In his final game for the 49ers, against the Indianapolis Colts in Week 5, Bowman played 58 of 76 defensive plays, well short of his usual full workload in which he rarely comes off the field.
After that game, Bowman voiced his frustration to reporters, acknowledging he did not like the decision to get him extra rest. He repeatedly said "I don't know" when asked if he at least understood the rationale behind it.
With the Raiders, Bowman is expected to help shore up the middle of the run defense -- which is ranked No. 21 in the NFL, giving up 117.2 rushing yards per game -- even as he saw himself coming off the field in passing situations for the Niners in their new 4-3 scheme this season.
The Raiders (2-4) have lost four straight games and are in danger of falling out of a playoff race in October with the Chiefs (5-1) having won five straight against Oakland.
ESPN's Adam Schefter and Nick Wagoner contributed to this report.