In a jubilant locker room, the first-year coach gave a victory speech that is becoming commonplace these days for the turnaround Niners, who enter their bye week with a 5-1 record and commanding 2½-game lead in the NFC West, a division of which San Francisco hasn’t been champion since 2002.
"There's something about this team now," Harbaugh yelled above the locker room din. "It's building, something remarkable is going on here."
That much has been hard to argue six weeks into the season.
At this point, the 49ers have to be the NFL's biggest surprise. Not only are they 5-1 – they could be undefeated if not for a late letdown in a Week 2 overtime loss against Dallas, a game San Francisco led by 10 points in the fourth quarter – but they've also won three consecutive road games against the 4-2 Bengals, the heavily-favored Eagles and last week against the now 5-1 Lions.
San Francisco also has five games left within the weak NFC West, where the Niners’ three divisional rivals currently have a combined 3-12 record.
The question everybody is asking is, how are the 49ers doing it?
Many of the players will tell you that it's coaching. The 49ers have been taking on the character of their fiery new head coach.
"His whole demeanor just kind of rubs off on the players," offensive tackle Joe Staley said. "You can see first-hand how competitive he is, how much emotion he shows. I think that's really something positive for this team."
Said defensive tackle Ricky Jean Francois, “It's almost like he's still playing football. He's with us. Just to see a coach fired up, to see him jumping with you, slapping five, patting you on the back, telling you good job and stuff and he's into the game. That's our energy right there."
Beyond motivation, Harbaugh and his staff also know a little something about X’s and O’s and preparing their players.
Indeed, after a disappointing 6-10 season last year in which the young players seemed to have regressed, the 49ers are getting tremendous contributions this season from their youngsters.
Here are two notable examples on an opportunistic defense that has continually risen to the occasion this year while establishing itself as one of the NFL’s best:
--- Linebacker NaVorro Bowman: As a rookie last year, Bowman couldn't even stay on his feet and was eventually benched as a nickel linebacker. This season, Bowman is out-playing his perennial All-Pro cohort Patrick Willis. He's an excellent blitzer, a solid coverage player and a prolific tackler.
Willis said that sometimes when Bowman was in the game last year, Willis felt he was on his own out there. Not this year. Bowman is fifth in the NFL in tackles and did an excellent job covering Lions running back Jahvid Best, just like he has done against the opponent’s top threats virtually every week.
--- Safety Dashon Goldson: The hard-hitting Goldson appeared to be on the verge of Pro Bowl recognition after the 2009 season. That year he caused three fumbles, intercepted four passes, defended six passes, and made 94 tackles including two sacks. Last year, he dropped to 80 tackles, no forced fumbles and one interception.
Now Goldson is back to his 2009 self, particularly with his tackling. He has knocked two running backs out of consecutive games (Tampa Bay's LeGarrette Blount with a knee injury, and Detroit's Jahvid Best with a concussion). He has forced a fumble and recovered one.
Then there's quarterback Alex Smith, who's enjoying the best year of his career with a robust quarterback rating of 95.2.
Smith had his worst game of the season last week in Detroit, but he still came through with the winning touchdown pass on a clutch fourth-and-goal play, the first time in Smith’s seven-year career that he has thrown for the winning score in the final two minutes of a game.
Not only are the careers of some players getting resurrected, but the team is also getting terrific play from its rookie class.
First-round pick Aldon Smith is fifth in the NFL with 5.5 sacks and has four in the last two games. Smith is also catching on quickly to his responsibilities as an outside linebacker.
Meanwhile, third-round pick Chris Culliver has supplanted veteran Shawntae Spencer as the team's nickel corner and had an excellent performance last week against Detroit and star receiver Calvin Johnson.
"His confidence is growing, coaches' confidence in Chris is growing," Harbaugh said. "Go back to that a few months ago, if you can just get a percent better each day, after 30 days we'll be 30 percent better. I think Chris really encapsulates that, and he's playing extremely well on special teams too."
Fourth-round pick Kendall Hunter now spells Frank Gore consistently and has been averaging between nine and 10 carries a game. Coaches are also unafraid to put Hunter in at crucial times. Even though Gore has climbed to fifth among the NFL’s leading rushers during a sensational three-game stretch, Hunter still has been getting his carries and making a contribution while averaging 4.5 yards a carry.
The surprise of the draft class may be fullback Bruce Miller. A defensive end at Central Florida last year, Miller converted to fullback this season, and he has been a solid lead blocker. He also has been a dependable receiver and provided a different dimension at the position after taking over as the starting fullback when veteran Moran Norris broke his leg in September.
Lastly, Colin Jones is just what the 49ers wanted when they took the TCU safety in the sixth round. Jones uses his blazing straight-line speed to cover kicks and punts; he's often the first guy to make the tackle.
If Harbaugh feels something is building and something remarkable is happening, he may have his own coaching staff to thank for it.
Offensive coordinator Greg Roman and defensive chief Vic Fangio both followed Harbaugh from Stanford to the 49ers, and both have been calling excellent games on their respective sides of the football.
Fangio, in fact, had an excellent strategy last week to contain Detroit’s explosive offense that Harbaugh said was one of the best games by a defense he has ever seen.
“Vic Fangio had a tremendous plan,” Harbaugh said. “Vic talks about packing the defense for the road games, and that’s what you need to do. Vic thought it was the best defensive game that he's been a part of, and it was just outstanding.”
The 49ers’ outstanding start to the season and strong finish in Detroit had the team’s spirit and camaraderie extending outside the locker room and traveling with the Niners on the way home, where a week off for the players would be waiting.
"When we got back on that plane, most people say that's a long trip but it felt short because everyone was on the plane smiling, still giving each other high-fives," Francois said. "It felt like we were in the locker room but we were in an airplane at 45,000 feet in the sky."
That sky-high feeling is spreading all around the 49ers, not to mention those who follow them.