Smarter Stats: New Orleans Saints at San Francisco 49ers

This is the first in a series of previews that will take a closer look at each divisional-round matchup, using advanced metrics and game tape observations. We begin with the matchup that will see the New Orleans Saints travel to the Bay Area to meet the San Francisco 49ers.

When: Saturday, 4:30 p.m. ET
Where: Candlestick Park

This may be the most interesting stylistic fight of the weekend and it starts with the quarterbacks:  how they do and how defenses try to stop them.

Alex Smith may not be flashy but he certainly is careful with the football. He leads the league in interception percentage (1.1 percent, just five picks in 446 attempts), which tells us that even when he throws erratically, he's erratic enough that nobody can catch the ball on either team. Jim Harbaugh has stressed the importance of smart passing and it's taken hold. This is especially impressive considering the number of times Smith was pressured through the season. Not only was Smith sacked 44 times, more than any other quarterback in 2011, but per Football Outsiders, he received 88 quarterback hits (contact during or after throws), which was the second-highest — only Seattle's Tarvaris Jackson was hit more often.

The 49ers' offensive line obviously doesn't handle blitzes well — this is something that shows up on tape as much as it does on the stat sheets — and that could be a problem against Gregg Williams' defense. Per Greg Cosell on this week's podcast, Williams was among the league leaders in sending blitzes against the pass … but he was also very high in percentage of times in which he'd rush three and drop eight. San Francisco's inexperienced line will likely struggle to pick up everything that Williams throws at them.

The Saints don't really have a pure pass rusher right now — it's safe to say that more was expected of rookie Cameron Jordan — but that doesn't mean that Williams' guys don't annoy passers. New Orleans totaled 87 quarterback hits, above the league average (the Houston Texans ranked first with 115, which is bad news for Joe Flacco). Interestingly enough, safety Roman Harper led the team in QB hits with nine, and he's generally a much better blitz guy than he is in coverage. End Will Smith led all Saints linemen with eight and Jordan had just two.

Another point of concern about San Francisco's offensive line: Based on FO's Adjusted Line Yards metrics, it's pretty clear that the success of the 49ers' running game is a bit more about the backs. That line ranked 21st in Offensive ALY at 3.98 yards per carry, but higher in actual running back yards with 4.17 per carry. The offense declined in most short-yardage situations and enjoyed a serious upturn in productivity when the backs were 10 or more yards upfield (when linemen are far less a factor). In other words, if Frank Gore and Kendall Hunter want to make hay against New Orleans, it will be on their shoulders to get it done.

The good news for Gore and Hunter is that their efforts should play right into New Orleans' biggest defensive weakness.  The Saints were average on defensive ALY, but they were dead last in the NFL in stopping those open-field carries 10 or more yards beyond the line of scrimmage. This will be especially true if the Saints continue their recent trend of playing a lot of Tampa 2 looks in which middle linebacker Jonathan Vilma drops into coverage.

Drew Brees may have a preternatural ability to deflect pressure with motion, quick passes and route concepts that take potential blitzers away from the front, but he'll have his hands full with the 49ers' pass rush. Rookie endbacker Aldon Smith had 14 QB hits in addition to his 14 sacks, and the facilitator for many of those sacks — the amazing Justin Smith — had seven hits of his own despite being at least double-teamed on most plays. The 49ers had 102 hits overall, third behind the Houston Texans and Cincinnati Bengals.

Still, that Mr. Brees can be a pain to bring down. He was sacked just 24 times on 657 pass attempts and was hit just 53 times, which is a rather impressive percentage for such a mobile quarterback. He's the best in the game at getting the ball away just as the defenders arrive.

[Related: 49ers pass rusher Aldon Smith talks to Yahoo! Sports Radio]

As is the case with many great quarterbacks who play their home games in a domed stadium, we have to look at (and sometimes dispel) the notion that those quarterbacks are hothouse flowers who will disintegrate under the elements. Brees is a bit more mortal outdoors, but not by much — and according to all forecasts, it promises to be unseasonably warm in the Bay Area this weekend.

Through the regular season, Brees completed 191 of his 274 passes out of doors (a 69.7 completion rate) for 2,219 yards (8.10 YPA), 12 touchdowns and eight interceptions. He was also sacked 12 times outside, and the sacks and turnovers could be of some concern.  Not only do the 49ers get after the passer at a furious rate, but they also led the NFL in turnover +/- with 28 more takeaways than giveaways and 23 interceptions.

Each of these quarterbacks is special on one specific down. First down belongs to Alex Smith, who is 113 of 171 for 1,363 yards, seven touchdowns and just one pick. He tends to revert later in the downs, so the Saints should watch out for the first-down passes that would seem to be out of character for such a run-heavy team.

Third down belongs to Brees, and if you want to make him err, first down is the time to do that. On all third-down passes, he's been supernatural: 109 of 151 for 1,440 yards 14 touchdowns and two picks. First down's a little tougher: 202 of 284 for 2,159 yards, 19 touchdowns and eight interceptions.

It's an interesting set of matchups: the Saints are probably more run-based and physical than people give them credit for (they remind me of the Don Coryell Chargers and the "Greatest Show on Turf" St. Louis Rams in that regard), while the 49ers are more opportunistic on both sides of the ball than their supposedly stodgy, fundamentals-based approach would lead you to believe.

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