There have been rumblings that the defense isn't playing up to snuff so far this year. Looking at the scores against the Cardinals and the Seahawks, that would appear true. But in watching the first two games, I've been impressed with the defense. They've haven't been gashed for big plays, save one long pass to Steve Breaston in week 1 and the TD run by Julius Jones on a safety blitz in week 2. In fact, the 49ers defense is currently in the top 10 in the league in yards allowed/play and 20 + yard plays allowed. Plus they've got sacks and turnovers. What more could you ask? So if they've been so good at limiting opposing offenses, why are they allowing so many points?
The answer, like all things this year, has something to do with Mike Martz. Specifically, the Martzian offense is not giving the defense much help in terms of field position. Field positions is a simple metric, but the implications are more complex. If a defense has the offense pinned back against their own goal line, the defense can be more aggressive with blitzes, stunts, and coverages. Conversely, when the offense has the defense near their own endzone, the defense has to play more conservatively and can't afford exotic and risky blitzes. Welcome to life on Martz.
To illustrate how the defense has been given a shitty lot the last few weeks, I'm using two field positions stats. First, I looked at how many the points the defense has given up when the opponents' offense starts with a turnover-induced short field. Second, special teams has been putting the defense in terrible situations with poor coverage on punts, so I looked at the drive charts to see where the other teams are starting their drives after the offense punts.
When looking at these numbers, keep two things in mind. First, the average starting field position for most teams over the course of a season is between their own 25- and their own 30-yard line. Second, the team that averages a better starting field position than their opponent almost always wins. Pat Kirwan ran a nice story documenting this last year and the guy at Advanced NFL Stats (a nice site) gave the argument a more mathy support.
First, turnovers. The Martz offense has turned the ball over six times in two weeks. Here's the opponents' average starting field position after turnovers and how the defense has fared in response.
Opponents' avg. starting field position after turnovers: 49ers' 26-yard line
Total points allowed by the defense after 6 turnovers: 10 ... total!
That's pretty impressive if you ask me. Yes, the stats are skewed because the Seahawks recovered a fumble and scored without ever letting the defense take the field, but even subtracting that turnover from the calculation the defense has still responded well to turnovers.
As for the punting unit, the comparison is simple because there have been just as many punts (six) as turnovers. Here are the stats.
Opponents' avg. starting field position after punts: Own 44-yard line
Total points allowed by the defense after 6 punts: 23
There are two things that lead to this abnormal starting field position the punting unit is allowing. First is the punting unit itself. Andy Lee's 45-yard average is good for 13th in the league. That's not terrible. It's the coverage that's killing the team. In spite of Lee's decent average punt, the punting unit is 30th in the league in net avg. That means they are allowing big returns. And from who? Steve Breaston and Michael Bumpus? WTF? The other thing that leads to this field position is the place on the field from which the team is punting. This is on Martz. If the offense is punting from deep in its own territory, the aren't helping the defense. I should mention here that 6 punts ties the offense for 3rd fewest punts in the league. Thank god.
These numbers are nothing to sneeze at - field position is important. Consider the average starting field position the offense is giving the opponents. Excluding kickoffs, the opponents' average starting field position is the 49ers' 41-yard line. That's just awful. Against the Cardinals, the 49ers gave up starting field position of the 49ers' 47-yard line INCLUDING KICKOFFS! There's no way you can win a game when the opponent starts in your territory more than they start in their own.
I have a deep fear that one of the side effects of the Martzian offense is a tendency to give up the ball deep in your own territory. If that's the case, look for the defense's numbers to sag this year even though they are playing well. As well as can be expected, anyway, for a defense with its back pinned against the wall. Hopefully, the offense can pick up the slack and keep the defense off the ropes. If not, every week is going to be a shootout.
