How does an NFL team face a "must-win game" in Week 4?When that team is off to a 1-2 start despite entering the season with legit aspirations, plays in a tough division and develops a knack for imploding after halftime.That was the backdrop for the on Sunday.And the perceived game of the day lived up to the hype, as the host Niners won a wild one, , over the previously undefeated .San Francisco, despite what some critics have said in recent weeks, still oozes talent. And this team has heart and character. It would've been foolish to write the epitaph on the 2014 before the end of September. They are just too good.Defensive coordinator Vic Fangio gets the game ball for this triumph. San Francisco's defense didn't allow ' Derrick White Jersey s high-powered offense into the end zone once, as the notched their 21 points on , and .The ' defense frustrated for four quarters, as Philadelphia's QB completed just 21 of his 43 pa ses for 195 yards (a lackluster 4.5 yards per attempt) and threw a pair of interceptions. San Francisco took complete advantage of a banged-up offensive line, completely bottling up , who Tim Duncan Jersey was a stunning non-factor with 17 yards on 10 rushes. And with the game on the line late in the fourth quarter, the Niners came up with a fantastic goal-line stand, . All in all, Kelly's squad managed just 213 yards of total offense. That's a remarkable accomplishment for the Niners.This defense remains one of the best in the game. Sunday proved it again. Just wait until Fangio gets (San Francisco's best defensive player) back from injury and (San Francisco's best pa s rusher) back from suspension.In addition to strong defense, a potent running game has always been a trademark of 's . We've been wondering aloud where has been to start the year. San Francisco's refusal to feed him the ball in the first three weeks -- when Gore averaged just 12.3 touches per game -- was batty. Since 2012, the Niners are 16-1-1 when Gore logs 17-plus carries. In a related story, Gore pounded Philly for 119 rushing yards on 24 carries, adding for good measure. Yes, rookie is a very promising young back who can spell Gore, but . Given the pa s-happy state of today's NFL -- and the Niners' shiny toys at receiver and tight end -- it's easy to see how San Francisco could be tempted to take to the air. But Gore is the bread and butter of this unit; the offense must always go through him.Now, despite this huge win, I'd be remi s if I didn't bring up the biggest looming concern by the Bay: San Francisco isn't going anywhere if doesn't clean up his play. in the preseason. For this team to make the playoffs at all, the quarterback must DeMar DeRozan Jersey improve.Look, there were moments of greatne s from Kaepernick on Sunday. He picked up a key first down to extend a fourth-quarter scoring drive with a designed run on third-and-13. And wasn't just a thing of beauty; it was a gigantic breakthrough score. Remember, in the first three weeks of the season, San Francisco was outscored 52-3 after the break. Shockingly, Kaepernick-to-Johnson was the ' first second-half touchdown of the 2014 campaign.Throughout the course of the game, though, Kaepernick was hardly accurate -- or savvy. Harbaugh couldn't believe when at the Chimezie Metu Jersey beginning of the fourth quarter. On the next drive, Kaepernick lost track of the play clock in the red zone, and the resulting delay-of-game penalty turned a third-and-3 from the Philly 11 into a third-and-8 from the 16. The Niners ended up settling for a field goal.And something very telling happened after the Niners' aforementioned goal-line stand. Harbaugh refused to let Kaepernick throw the ball. He didn't trust the fourth-year pro to put the game away. The Niners ran the ball three times, knowing Philly could call timeouts and get the ball back with a reasonable amount of time on the clock.And here's what hits you: It was the right call.Harbaugh was more confident putting his defense back on the field to secure Dennis Rodman Jersey the victory, which was understandable, given how things played out on Sunday.I'm a big believer in Kaepernick's promise, but he has to clean up his game to take San Francisco to the next level. I know he's capable of taking over games, but he just hasn't consistently looked like a big-time quarterback for more than a year now.Still, the are 2-2, and with and on tap, there's no reason this team shouldn't be 4-2 heading into in Week 7.I very much still believe in these Niners. I think reports of their demise have been greatly overstated. And I'm not surprised they handed the their first lo s of the season on Sunday.But the margin for error in the NFC -- and specifically, the NFC West -- is slim.I know the ' defense and run game will be up to the challenge.The quarterback has to join the party.Follow Adam Schein on Twitter .