After finally resembling a barely drafted rookie for two quarters Saturday, Brock Purdy returned to his now-regular role: seventh-round sensation.
The San Francisco 49ers quarterback shrugged off an ordinary opening and lit up Washington’s fourth-ranked defense with a series of second-half big plays in a 37-20 win on Saturday at Levi’s Stadium.
Purdy, 22, became the first rookie in franchise history to win each of his first three starts. And he did so after posting a puny passer rating (25.0) in the first 30 minutes. Purdy responded with a third-quarter explosion that included touchdown passes of 34 and 33 yards to Pro Bowl tight end George Kittle and a 54-yard toss to wideout Brandon Aiyuk that set up another score.
As a result, the 49ers, who were tied 7-7 at halftime, took a 24-14 lead after Robbie Gould’s 26-yard field goal opened the fourth quarter.
The 49ers’ eighth straight victory ran their record to 11-4 and kept them on the heels of the Vikings (12-3) in their quest to land the NFC’s second seed in the postseason. The 49ers are in position to leapfrog Minnesota if they have identical records by virtue of their record (9-2) in conference games.
Purdy completed 15 of 22 passes for 234 yards, a career-high, with two touchdowns and a pick (114.6 rating). And those numbers looked unlikely after a first half in which he connected on just 4 of 9 passes for 55 yards with an interception that wasn’t his fault: Purdy’s on target, over-the-middle pass to Jauan Jennings was bobbled and picked off on the carom by safety Darrick Forrest.
San Francisco 49ers quarterback Brock Purdy throws to a receiver in the first half of an NFL football game against the Washington Commanders, Saturday, Dec. 24, 2022, in Santa Clara, Calif. (AP Photo/Jed Jacobsohn)
Jed Jacobsohn, FRE / Associated Press• Pro Bowl pass rusher Nick Bosa did his best to place a stranglehold on the NFL Defensive Player of the Year award with his latest dominant and disruptive performance.
Bosa had two sacks and added another quarterback takedown that didn’t count on the stat sheet: Bosa dropped QB Carson Wentz on a two-point conversion attempt with the 49ers leading 30-20 with 5:30 left.
The takedowns gave Bosa a career-high 17.5 sacks, which leads the NFL and gives him a chance to match or break Aldon Smith’s franchise record of 19.5 set in 2012.
Bosa’s second sack, which came with the 49ers leading 24-14 early in the fourth quarter, was his most impactful: Bosa drilled QB Taylor Heinicke in mid-throw, forcing a fumble that defensive end Jordan Willis recovered at Washington’s 11-yard line. The takeaway led to a 23-yard field goal by Gould.
• Two days after do-it-all wide receiver Deebo Samuel was sidelined with knee and ankle injuries on Dec. 11, head coach Kyle Shanahan was asked about wideout Ray-Ray McCloud assuming some of Samuel’s various duties.
“Yeah, you can use them similarly,” Shanahan said. “They definitely have different bodies, I think that’s pretty obvious. But don’t tell Ray-Ray that. He gets extremely offended.”
The 190-pound McCloud, about 25 pounds lighter than Samuel, did a decent Deebo impression in the second quarter: McCloud took a Jet sweep and wasn’t touched as he ran 71 yards down the right sideline on an exquisitely blocked play in which Kittle , running back Christian McCaffrey, wide receiver Willie Snead and right tackle Mike McGlinchey cleared out defenders.

Ray-Ray McCloud (3) into the end zone for a touchdown in the first half as the San Francisco 49ers played the Washington Commanders at Levi’s Stadium in Santa Clara, Calif., on Saturday, December 24, 2022.
Carlos Avila Gonzalez, Staff Photographer / The ChronicleThe touchdown run was a career-long for McCloud.
• Running back Jordan Mason was questionable to play with a hamstring injury. And the undrafted rookie was down on the field with an apparent knee issue after the opening kickoff.
Mason wasn’t forced to leave the game, but it’s possible the impressive undrafted rookie didn’t receive a carry for the first time in six games because he was a bit banged up.
Mason ceded his backfield workload to rookie Ty Davis-Price, whom he supplanted on the depth chart. Davis-Price, a third-round pick, had his first carries since Oct. 23 and rushed for 30 yards on nine attempts.
Davis-Price has 67 yards on 25 carries this season, Mason has 217 yards on 33 carries.
Eric Branch covers the 49ers for The San Francisco Chronicle. Email: ebranch@sfchronicle.com Twitter: @Eric_Branch