Yesterday, we looked at what Tennessee’s offensive explosion in week 1 might mean for the rest of the year. Today, let’s do the same but for the 49ers defense. The 49ers were 2.5-point underdogs against Minnesota in week one, and the Over/Under in the game was 41.5 points. This translates to a projected a final score of 22-19.5 in favor of Minnesota. As it turns out, San Francisco won the game, 20-3, which means the Vikings were held 19 points below their expected total. That’s the 4th best performance by a team by this methodology since 2002.
The most impressive game? That came in 2003, in the Lawyer Milloy game. The Bills shut out New England, 31-0, while the pre-game spread projected New England to score 21.75 points. That wasn’t a sign that Buffalo was about to break through (the team finished 6-10), but it did provide some insight into a Bills defense that jumped from 27th (in 2002) to 5th (in 2003) in points allowed.
But, as it turns out, the way a defense performed in week 1 doesn’t usually portend such a big jump. There were 33 teams that allowed 14 or fewer points than expectation in week 1 since 2002. On average, these teams ranked about 19th in points allowed the prior year, and jumped about five spots to 14th that season. But a good chunk of that change was due to the great week 1 performance. On average, these teams allowed 22.6 points per game the prior year, 20.7 points per game the season in question, but 21.7 points per game in the remaining 15 games.
| Tm | Year | Boxscore | Wk 1 Exp PA | Wk 1 PA | Diff | Yr N-1 Rk | Yr N Rk | Diff |
|---|---|---|---|---|---|---|---|---|
| BUF | 2003 | Boxscore | 21.75 | 0 | -21.75 | 27 | 5 | 22 |
| TAM | 2003 | Boxscore | 19.5 | 0 | -19.5 | 1 | 4 | -3 |
| SDG | 2006 | Boxscore | 19.25 | 0 | -19.25 | 13 | 7 | 6 |
| DET | 2005 | Boxscore | 21.5 | 3 | -18.5 | 18 | 21 | -3 |
| BAL | 2006 | Boxscore | 18 | 0 | -18 | 10 | 1 | 9 |
| NYJ | 2009 | Boxscore | 24.75 | 7 | -17.75 | 18 | 1 | 17 |
| MIN | 2014 | Boxscore | 23.5 | 6 | -17.5 | 32 | 11 | 21 |
| CLE | 2004 | Boxscore | 20.25 | 3 | -17.25 | 12 | 24 | -12 |
| KAN | 2013 | Boxscore | 19 | 2 | -17 | 25 | 5 | 20 |
| SEA | 2009 | Boxscore | 17 | 0 | -17 | 25 | 25 | 0 |
| IND | 2003 | Boxscore | 23 | 6 | -17 | 7 | 20 | -13 |
| DEN | 2009 | Boxscore | 23 | 7 | -16 | 30 | 12 | 18 |
| CLE | 2003 | Boxscore | 25 | 9 | -16 | 10 | 12 | -2 |
| DET | 2006 | Boxscore | 25 | 9 | -16 | 21 | 30 | -9 |
| KAN | 2005 | Boxscore | 22.75 | 7 | -15.75 | 29 | 16 | 13 |
| ATL | 2006 | Boxscore | 21.75 | 6 | -15.75 | 18 | 15 | 3 |
| CHI | 2006 | Boxscore | 15.75 | 0 | -15.75 | 1 | 3 | -2 |
| SDG | 2007 | Boxscore | 18.25 | 3 | -15.25 | 7 | 5 | 2 |
| HOU | 2014 | Boxscore | 21 | 6 | -15 | 24 | 7 | 17 |
| IND | 2005 | Boxscore | 22 | 7 | -15 | 19 | 2 | 17 |
| TEN | 2013 | Boxscore | 24 | 9 | -15 | 32 | 16 | 16 |
| PHI | 2008 | Boxscore | 18 | 3 | -15 | 9 | 4 | 5 |
| STL | 2006 | Boxscore | 24.75 | 10 | -14.75 | 31 | 28 | 3 |
| BUF | 2011 | Boxscore | 21.75 | 7 | -14.75 | 28 | 30 | -2 |
| HOU | 2007 | Boxscore | 17.5 | 3 | -14.5 | 25 | 22 | 3 |
| WAS | 2010 | Boxscore | 21.5 | 7 | -14.5 | 18 | 21 | -3 |
| TAM | 2012 | Boxscore | 24.25 | 10 | -14.25 | 32 | 23 | 9 |
| SEA | 2004 | Boxscore | 21.25 | 7 | -14.25 | 15 | 22 | -7 |
| IND | 2007 | Boxscore | 24 | 10 | -14 | 23 | 1 | 22 |
| CIN | 2006 | Boxscore | 24 | 10 | -14 | 22 | 17 | 5 |
| SEA | 2010 | Boxscore | 20 | 6 | -14 | 25 | 25 | 0 |
| CHI | 2008 | Boxscore | 27 | 13 | -14 | 16 | 16 | 0 |
| SDG | 2002 | Boxscore | 20 | 6 | -14 | 16 | 22 | -6 |
| Average | 21.5 | 5.5 | -16.0 | 19.4 | 14.3 | 5.0 |
The 49ers ranked in the top 3 in points allowed for three straight years beginning in 2011, before dropping to 10th last year. Given the incredible turnover since then — just two of the defensive starters that played in Super Bowl XLVII — it would be easy to assume that San Francisco’s defense would decline in 2015.
For what it’s worth, if you look at the table above, there were seven defenses that ranked in the top 10 in points allowed in Year N-1, and all but one of those defenses (the ’03 Colts) remained very good in Year N. That’s a good sign for San Francisco, which was bolstered by an impressive pass rush against the Vikings. NaVorro Bowman and Aaron Lynch led a unit that produced 16 quarterback hits and 5 sacks, and that’s not all about a poor Vikings offensive line.