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No team in the NFL represents how fleeting success can be more than the San Francisco 49ers.

Three seasons ago, they were in the Super Bowl. Two seasons ago, many considered them the best team in the NFC. The Green Bay Packers couldn't beat them. The Packers lost to the 49ers four straight times, twice in the playoffs.

Then there's this offseason. The 49ers have had multiple defections, including the early retirement of former University of Wisconsin linebacker Chris Borland. When Bovada released their annual offseason Super Bowl odds, the 49ers (40-to-1) were ranked 22nd in the NFL.

The Packers will return to San Francisco on the first Sunday of October. It'll be the third time they have played the 49ers on the road since 2013. The first was a 45-31 loss in the NFC divisional playoff round, the second a 34-28 loss in the 2013 opener.

In October, the Packers likely will be favored.

Three things to know about the 49ers

» Tomsula's road less traveled: Jim Tomsula started his coaching career as a strength and conditioning coach at Catawba College in Charleston, S.C. In his early years, it would have been hard to predict Tomsula would climb to the top of the coaching profession. He was a defensive line coach at a Pittsburgh high school, an assistant coach at Charleston Southern, and a defensive line coach in Germany as recently as a decade ago. Tomsula got his break when he was hired as the 49ers' defensive line coach in 2007, a job he held until last season. It's quite a jump to go from NFL position coach to a head coach in one season, though Tomsula was an interim head coach in 2010. Still, he'll try to prove the road less traveled can lead to success.

» Kaepernick still dangerous: Perhaps more than any other player, 49ers quarterback Colin Kaepernick has tormented Dom Capers' defense. In three games against the Packers, Kaepernick has yet to have a bad performance. His breakout performance came against the Packers three season ago, during the divisional-round playoff loss. Kaepernick had 263 passing yards, 181 rushing yards and four touchdowns that day. He's averaged 300 passing yards and 95 rushing yards, while scoring eight touchdowns with two interceptions, against the Packers. If you're looking for a reason the Packers could be upset in San Francisco, start with Kaepernick.

» Not the same defense: The 49ers' success of a couple of years ago rested on one of the league's most dominant defenses. When they went to the Super Bowl, the 49ers ranked second in the NFL with 17.1 points allowed per game and third with 294.4 yards allowed. Even going 8-8 last season, they ranked 10th with 21.3 points allowed per game and fifth with 321.4 yards allowed. However, that defense has been decimated by defections this offseason. Along with Borland, star linebacker Patrick Willis retired. With its core gone, expect the 49ers' defense to take a hit in 2015.

Packers schedule glimpse

Week before: "Monday Night Football" vs. Chiefs, Sept. 28

Week after: Rams, Oct. 11

On the horizon: Chargers, Oct. 18

— rwood@gannett.com and follow him on Twitter @ByRyanWood.

San Francisco 49ers

Coach: Jim Tomsula (first season).

2014 record: 8-8, 3rd NFC West.

Scoring offense: 19.1 points per game (25th in NFL).

Total offense: 327.4 yards per game (20th).

Scoring defense: 21.3 points allowed per game (10th).

Total defense: 321.4 yards allowed per game (5th).

Series: Packers lead 20-15 (4-3 in postseason).

Last meeting: The Packers came close to ending their losing streak against the 49ers on Jan. 5, 2014. The game was tied in the final minutes until San Francisco kicked a game-winning, 33-yard field goal to make it 23-20 on the final play. Aaron Rodgers was efficient, if not overpowering, completing 17-of-26 passes for 177 yards and a touchdown. On the other side, 49ers quarterback Colin Kaepernick gave the Packers' defense fits, throwing for 227 yards and adding 98 on the ground.

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