The teams meet again Sunday at the site of Super Bowl 50, though neither currently resembles a serious title contender.
Though no longer sharing coaches with the same last name, several similarities still exist between the clubs in the first head-to-head matchup since John Harbaugh's Ravens outlasted brother Jim's 49ers 34-31 in Super Bowl XLVII three seasons ago. Both enter Levi's Stadium with 1-4 records and are coming off trying losses marred by a failure to protect a second-half lead.
''It's unfortunate that we're both in the same situation right now," Baltimore quarterback and Super Bowl XLVII MVP Joe Flacco said, ''because we feel as though we have a better team. I'm sure they feel the same way.''
In stark contrast to their 2012 Super Bowl seasons, defensive breakdowns have been prevalent during each team's poor start. San Francisco has begun the post-Jim Harbaugh era by allowing 406.8 yards per game to rank 31st and Baltimore ranks 24th in total defense after surrendering 505 yards in last week's 33-30 home overtime loss to Cleveland.
Josh McCown set a franchise record with 457 passing yards in leading Cleveland back from a 21-9 third-quarter deficit, and the Browns converted 12 of 19 third-down chances while aided by 12 Baltimore penalties.
"We didn't cover the way we needed to, whether it was deep, whether it was intermediate or whether it was short," John Harbaugh said. "We didn't get the job done in coverage."
In-game injuries to cornerbacks Lardarius Webb and Will Davis and pass rusher Elvis Dumervil played a role in the struggles. Davis tore his ACL and was placed on injured reserve Tuesday, while Webb (thigh) and Dumervil (groin) are uncertain for this week.
Baltimore filled Davis' spot by signing veteran cornerback Shareece Wright, released by the 49ers last week after being a healthy inactive for the first four games.
The Ravens are expected to get two of Flacco's top targets back as they attempt to overcome the franchise's worst five-game start, with wide receiver Steve Smith and tight end Crockett Gillmore both returning to practice Wednesday.
Smith sat out against Cleveland after suffering several microfractures in his back during a 23-20 overtime victory at Pittsburgh in Week 4. The 36-year-old amassed 336 yards on 23 catches over his previous two games. Gillmore has missed the last two with a strained calf.
Justin Forsett, who's rushed for 271 yards over the past two weeks, is also expected to play despite hurting his ankle late in the Cleveland game.
The 49ers permitted 525 yards in their 30-27 Week 5 loss to the New York Giants, with Eli Manning capping a 441-yard, three-touchdown passing night with a go-ahead strike to Larry Donnell with 21 seconds remaining that completed an 8-play, 82-yard drive.
San Francisco is yielding 446.5 yards and 34.3 points in losing four straight since a 20-3 season-opening home win over Minnesota.
The 49ers also rank last in scoring (15.0 ppg) and 29th in total offense (307.2 ppg), though last week's 380-yard output was a sign of progress after being held under 200 in losses to Arizona and Green Bay.
"It's good offensively to get in a rhythm like that," he said. "It's something that we can build off moving forward, but we have to win games."
The 49ers should have Vernon Davis back from a two-game absence caused by a knee injury, with the two-time Pro Bowl tight end rejoining two former Ravens in wide receivers Anquan Boldin and Torrey Smith.
Boldin, coming off a season-best 8-catch, 107-yard output last week, had 104 yards on six receptions for Baltimore in Super Bowl XLVII. Torrey Smith compiled 213 catches and 30 touchdowns in four seasons with the Ravens before signing a five-year, $40 million deal with San Francisco in March.
Both also were part of Baltimore's 16-6 victory in the Harbaugh vs. Harbaugh Thanksgiving night matchup in 2011, the Ravens' third consecutive regular-season win over San Francisco. The 49ers' lone win in five all-time meetings came at Candlestick Park in 1996.