I’m going to hold off until Sunday morning to post my Super Bowl preview, but today, I’m going to look at a possible hidden key to the game. In most playoff games, each coach is faced with a critical fourth down decision. Often times the conservative coach delays the decision to go for it in favorable circumstances early in the game only to be forced to do so in less optimal situations in the final minutes. We also know that in general, coaches frequently fail to go for it early in games when the down and distance dictate a more aggressive approach: even Bill Belichick has been known to cost his team points with conservative fourth-down decisions, as he did in the AFC Championship Game. Which leads to today’s post: Is one Harbaugh more or less aggressive than the other?

Let’s start with how each coach has performed in the regular season, beginning with Jim.

• Since 2011, the 49ers have gone for it 26 times and converted 17 times (65.4%).
• San Francisco has gone for it on eight 4th-and-1 situations, converting five of seven times on runs and failing once on an Alex Smith pass.
• The 49ers went for it on 4th-and-2 or -3 on five different occasions, although three of those times the score differential was greater than 21 points. The 49ers converted on four of the five plays, all passing plays save an Alex Smith 17-yard run against the Bills that was probably a called pass.
• On 4th down with SF needing 4, 5, or 6 yards, the 49ers converted five of six attempts, all on passes.
• Ignoring some special teams fourth down plays, the 49ers only went for it four times on 4th and longer than 6. In the final minutes of the Ravens loss, Alex Smith couldn’t connect with Ted Ginn Jr. on 4th and 12; in the 3rd quarter against the Giants, trailing 23-3, Smith hit Vernon Davis for 7 yards on 4th and 15; on a meaningless 4th and 17 late in the blowout loss against the Seahawks, Colin Kaepernick threw an 18-yard touchdown to Delanie Walker, and Kaepernick threw a Hail Mary to Randy Moss at the end of the first half against the Rams (incomplete)
• San Francisco has gone for it on 4th down 13 times (including a fake field goal) when leading, converting ten of them.

To keep things even, I’m only going to analyze John on fourth down over the last two years. During that time:

• The Ravens have gone for it 21 times and converted 10 times (47.6%)
• Baltimore went for it 13 times on 4th-and-1, five times on 4th-and-3 through 5 (all in the fourth quarter), once on 4th and 10 down 30 points, once on 4th and 19 with 10 seconds left in the first half, and once on 4th and 29.
• On the 13 4th-and-1 plays, Baltimore converted only seven times. One of those was a fake punt by Sam Koch; of the other 12, the Ravens handed off to Ray Rice or Bernard Pierce six times and gained the first down only once. Joe Flacco ran for the first down three times (successful all three times) and passed three times (successful twice). The takeaway: the Ravens have struggled in traditional 4th-and-1 rushes. On the other hand, Baltimore was 25-for-32 (78%) on running back rushes on 3rd-and-1 the past two seasons, so perhaps this is not a significant concern.
• Baltimore has gone for it on 4th down eleven times (converting six) when leading or tied, and one of those was the Sam Koch fake field goal against the Raiders when Baltimore led by 30 points.
• In a similar vein, the Ravens have only gone for it four times in the first three quarters on 4th downs where they needed more than one yard, and all of those instances had extenuating circumstances.

So the 49ers have been more successful on 4th downs, and also seem more willing to go for it in less traditional circumstances. But we’re only analyzing half of the equation: what about those times when the teams punted when they shouldn’t have?

4th and 1, leading or trailing by 14 or fewer points

Excluding fakes and those circumstances where the score/time remaining dictate kicking, San Francisco has gone for it 8 times, punted 7 times, and kicked a field goal 9 times. Baltimore has punted it 8 times, but only kicked field goals twice in these situations. Baltimore went for it 10 times, converting six of them, although three of those were in the final two minutes of the fourth quarter. Still, I’d say John Harbaugh has been more aggressive in going for it on 4th-and-1 than his younger brother.

What if we look at 4th down in enemy territory, with two-to-four yards to go? San Francisco kicked a field goal 17 times, punted three times, and went for it twice (converting both times). That’s a pretty conservative track record for a coach with a struggling kicker, like David Akers. On the other hand, the Ravens have faced 4th and more than 1 yard to go, in their opponent’s territory, 62 times over the last two years, and have never gone for it. Let’s repeat: In the last two years, John Harbaugh has never gone for it on 4th down when he needed more than a yard in enemy territory except in games when the margin was four touchdowns.

John Harbaugh seems perfectly content to go for it on 4th-and-1, but otherwise, he’s not going to take any chances unless it’s a fake (he is a former special teams coach, after all) or the Ravens are trailing big. Jim Harbaugh is a little less risky on 4th-and-1 — perhaps that will change with Kaepernick under center — but he’s at least willing to take chances in less obvious situations..

This jives with what Jim Armstrong discovered in his 2011 Aggressive Index: he found Jim to be very aggressive and John much more timid. Over e-mail, Armstrong forwarded me the numbers he crunched for the 2012 season, although he has not yet posted them to Football Outsiders. Both coaches reverted to the mean, with John ranking as the 17th most aggressive coach and Jim as the 20th. According to Armstrong, “The Harbaughs seem pretty similar this year in 4th down tendencies, but John has been a bit more aggressive career-wise, mainly because he’s more willing to go for it on 4th-and-1 and in the maroon zone.” One thing is clear: neither of these coaches are anywhere near as aggressive as the people at Football Outsiders or Brian Burke would suggest they should be. In any event, the x-factor here is how David Akers’ struggles impact San Francisco’s 4th down decisions. While the sample size is small, San Francisco has been excellent on fourth downs, which should only make Harbaugh the younger more likely to be aggressive. However, watch out for a special teams fake by John (but Jim knows that John wants to do that, so John won’t, except John knows that Jim knows that John won’t because Jim knows that John wants to, so he will. Maybe.)

One final note: I said that all the above data was for the regular season only. In four career playoff games, Jim Harbaugh has never gone for it on 4th down, although in his defense, the circumstances haven’t been favorable to fans of aggressive strategy. San Francisco has only faced two 4th-and-1 situations, and the conservative approach was defensible (in field goal range with 3 seconds left in the half vs. Green Bay, in overtime at their own 31 against the Giants) each time. Even the 4th-and-2 situations were ones where all but the most aggressive coaches would have kicked. John Harbaugh hasn’t been much better: he went for it in desperation against the Broncos this year and the Patriots last year, but other than that, the Ravens have gone for it only once in the playoffs the last two years: on 4th and goal from the 1, up 4 with 17 minutes left, Baltimore ran Ray Rice (after Rice ran for 1 yard on 3rd-and-goal from the 2) and was stuffed.

There is likely to be a big fourth down opportunity during the Super Bowl. If you had to bet, the odds are the 49ers would be the team to take advantage of it.

In case you’ve missed it, here are some other articles that you might enjoy as we get ready for Super Bowl XLVII.

Previewing the NFC Championship Game: San Francisco at Atlanta
Previewing the AFC Championship Game: Baltimore at New England
Super Bowl History
Is Joe Flacco elite?
Super Bowl XLVII Prop Bets
How Super Bowl XLVII could impact the HOF chances of certain 49ers
How Super Bowl XLVII could impact the HOF chances of certain Ravens
Is good luck driving the low interception rates of Joe Flacco and Colin Kaepernick?
Checkdowns: How the Ravens and 49ers compare to previous Super Bowl teams
Super Bowl Squares: How to win your Pool at your Super Bowl Party