The 49ers are very good, but they have holes. In week 1, the Packers actually did a very good job exploiting those holes, eventually losing a close shootout 34-28. The 49ers didn't have many shootouts this season, though. They scored over 30 points 8 times, but the Packers were the only team to stay within a score of them when San Francisco scored that much.
The 49ers are a defense-first team, and as such they typically lost when an opponent managed to score on them. The Seahawks did in week 2, the Colts did in week 3, and the Saints did in week 11, and the 49ers lost all three of those games. Only the Packers and the Atlanta Falcons managed to put up 21+ points on the 49ers and still lose. While the 49ers defense is very good, they're not an all-time juggernaut by any stretch, and teams with good offenses have been able to put up points on them.
For example, here are the games with the highest number of points San Francisco allowed on the year, the quarterback they played in that game, and that QB's ranking according to Pro Football Focus grades.
|Points Allowed||QB||PFF Rank|
|29||Russell Wilson (SEA)||4|
|28||Aaron Rodgers (GB)||8|
|27||Andrew Luck (IND)||T-13|
|23||Matt Ryan (ATL)||T-13|
|23||Drew Brees (NO)||3|
Contrast that with the teams they held to the fewest points in individual games this season:
|Points Allowed||QB||PFF Rank|
|3||Matt Schaub (HOU)||38|
|6||Robert Griffin III (WAS)||30|
|10||Cam Newton (CAR)||15|
|10||Chad Henne (JAX)||42|
|11||Sam Bradford (STL)||21|
This is not terribly surprising, but it's worth pointing out that if the 49ers are facing a good offense they're going to have to do some scoring of their own and that hasn't always been easy. Colin Kaepernick graded out as Pro Football Focus's 18th-best passer, just 0.7 points ahead of Carson Palmer. Frank Gore has a solid overall grade at 13th, but that gets a huge boost from his league leading 10.7 grade in pass blocking and he really faded down the stretch. As a pure runner he is only 21st, just behind Montee Ball and Ben Tate. Anquan Boldin is a fine slot receiver and Vernon Davis is one of the better tight ends in football, but in general this has not been an offense that scares anyone other than the Packers.
The good news for Packer fans is that the 49ers have been notably less effective on offense over the second half of the season. In the first half, the 49ers averaged 27.3 points per game and held opponents to an average of 18.1. In the second half, their defense improved a bit to allowing 15.9 points per game, but their offense declined substantially to 23.5. Another big indicator of the decline of the San Francisco offense is the workload of field goal kicker Phil Dawson. In the first half of the season, Phil Dawson was 9 of 12 on FG attempts. In the second half Dawson was 23 for 24. Far more 49er drives stalled out in field goal range down the stretch.
Figuring out exactly why this is was actually a bit difficult. By most measures, Colin Kaepernick actually played better in the 2nd half of the season than in the first half. He had a higher completion percentage (60% to 55%), higher adjusted yards per attempt (7.9 to 7.4) and much better TD to INT ratio (9-5 in the first half, 12-3 in the 2nd half). As I see it, there were 2 main factors.
1. Kaepernick was more patient with the ball, but as a result he took far more sacks.
In the first 6 games of the season, Kaepernick turned the ball over 9 times, throwing 5 picks and losing 4 fumbles. I speculate that sometime after that he changed his style to holding onto the ball longer, running less frequently, standing in the pocket longer, and taking more hits and more sacks. In some ways this paid off, as you can see from the his turnover numbers, and his passing numbers didn't suffer much if at all. However, sacks also serve to put you in bad down-and-distance situations. In the first half of the season he was sacked 15 times, or once every 13 dropbacks. In the 2nd half he was sacked 24 times, or once every 9 dropbacks.
Also worth keeping in mind, Pro Football Focus tracks how quarterbacks perform under pressure, and Kaepernick is ranked as the 6th-least accurate passer in the league when under duress. The only players behind him in Adjusted Accuracy Under Pressure are Matt Schaub, Sam Bradford, Brandon Weeden, Matt McGloin, and Thaddeus Lewis. He's just behind Geno Smith. This is probably why his superficial numbers improved when he started eating the ball more. When he's pressured he's a bad passer.
2. Frank Gore declined.
The 49er run game has served them well for years and Frank Gore has been a productive running back for longer than most, but age (Gore is now 30) and workload may be starting to catch up to him. In the first half Gore averaged an efficient 4.3 yards per carry while getting 18 carries a game and also contributing occasionally in the passing game (1 catch for 12 yards on average). In the second half, he only averaged 3.76 YPC while only seeing 16.3 carries per game, and he has all but disappeared from the passing game, catching only 1 ball for 6 yards over the last 4 games. In the second half he averaged just 5.6 yards per reception on only 8 catches.
Gore has had some truly confounding games as well. He lit up the Seattle run defense in San Francisco in week 13, rushing 17 times for 110 yards, but just one week before he was completely stymied (13 carries, 31 yards) by a Washington defense that didn't stop anyone. There's no shame in being shut down by the Cardinals' elite defense (13 carries for 14 yards), but Tampa also held him under 4 YPC. Gore still had the occasional good game and it doesn't take an elite back to put up numbers on the Packer defense, but this is not the same back the Packers faced in week 1.
It's easy to see how all of those first half touchdowns turned into second half field goals. A struggling running back will put you in passing situations, and taking sacks in those passing situations will often lead to settling for a field goal range instead of trying to convert a 3rd and 15 for a first down.
The Packers' defense remains bad, and bad in a way that plays to the strength of the 49ers' offense. It was no accident when Anquan Boldin and Vernon Davis lit them up in week 1, as the Packer safeties and inside linebackers struggled mightily in pass coverage, but that game was played by a 49ers team with a slightly better running back and a quarterback who was still taking chances.
It's hard for a quarterback to shift his style of play from one game to the next and if the more careful version of Kaepernick shows up on Sunday, it's at least possible that he and his offense will not be able to keep up with a fully-loaded Packers attack.