A double post at the New York Times this week.

Did you know that Alex Smith is seven attempts away from qualifying for eligibility for certain rate-based statistics? If Jim Harbaugh wants to game the system — and this is Harbaugh — he could ptobably that Smith breaks the completion percentage record, set by Drew Brees in 2011.

I also looked at how the playoff field will be very familiar this year:

With two weeks remaining in the N.F.L. regular season, seven teams have clinched a playoff berth and several more can clinch this weekend. Chances are, two weeks from now, the teams in the playoffs will look pretty familiar to N.F.L. fans.

In the A.F.C. in 2011, the Patriots, the Ravens, the Texans and the Broncos won the East, North, South and West Divisions. New England, Houston and Denver have already clinched their divisions in 2012, and even the free-falling Ravens are still the favorites to win the A.F.C. North. That would give the conference four repeat division winners, a first since the league moved to the four-division format in 2002.

Last year, the Pittsburgh Steelers and Cincinnati Bengals were the two wild-card teams. Well, those two teams are currently battling for a wild-card spot, and it would be a surprise if both teams are left out of the playoffs. That would leave one spot in the A.F.C., which is most likely going to go to the Indianapolis Colts. The Colts did not make the playoffs in 2011 — in fact, the team had the worst record in the league — but they did make the playoffs every year from 2002 to 2010.

From 2009 to 2011, half of the conference — the Ravens (6), Jets (6), Patriots (5), Steelers (4), Colts (4), Broncos (2), Texans (2), and Bengals (2) — played in 31 of the A.F.C.’s 33 playoff games, and barring the miraculous (the 6-8 Dolphins are technically still alive), that won’t change this year. The last time a Tom Brady-led team didn’t make the playoffs was in 2002; the last time Peyton Manning’s team missed out on the postseason was in 2001. In the A.F.C., some things never change.

The N.F.C. features only slightly more turnover. Green Bay is going to the playoffs for the fourth straight season while Atlanta will be there for the fourth time in the five-year Matt Ryan/Mike Smith“>Mike Smith era. San Francisco has a good chance of securing a first-round bye for the second year in a row. That leaves just three remaining spots.

Seattle, winner of a playoff game just two years ago, is likely to be back in the postseason as well. The Giants, winners of two of the last five Super Bowls, will make the playoffs if they win their final two games. Chicago and Dallas are no strangers to the playoffs, and one might make it again this year. The real “surprise” teams in the N.F.C. are Minnesota — which did go to the N.F.C. championship game three years ago — and Washington. Andrew Luck and Robert Griffin III were the first two picks in the draft and may power their teams to the playoffs this year. When it comes to the 2012 season, that qualifies as unpredictable.

Your weekly updates on Adrian Peterson and Calvin Johnson

At this point, it’s getting impossible to write a statistical column without talking about Adrian Peterson“>Adrian Peterson. The Vikings gained just 322 yards against the Rams on Sunday, but Adrian Peterson“>Adrian Peterson ran for 212, accounting for 66 percent of the Minnesota offense. It was the fourth time this season — and in the last two months — that Peterson has rushed for at least 8 yards per carry on 15-plus carries; since 1960, only Barry Sanders (5) and Peterson have accomplished such a feat in a season.

In one of the most incredible stats of this or any year, Peterson has rushed for 1,313 yards in his last eight games, the most by a player in an eight-game stretch since at least 1960. From 1960 to 2011, only four men rushed for 1,200 yards in that span. In 1977, Walter Payton rushed for 1,221 yards over an eight-game stretch; three years later, Earl Campbell rushed for 1,245 yards in half a season. In 2005, Kansas City’s Larry Johnson gained 1,244 rushing yards in the last eight games of the year. Before Peterson, Eric Dickerson held the record for rushing yards in an eight-game stretch; Dickerson rushed for 1,292 yards in the last five games of the ’84 season and the first three games of 1985.

For more on Peterson and Calvin Johnson, along with some interesting week 15 stats, check the full article here.

Grading running backs can be tricky; rushing yards tell much of the story but remain a function of opportunity (itself an indicator of talent). Yards per carry sounds nice but often is more misleading than revealing. Last year at Smartfootball.com I analyzed team rushing games using rush success rate, and I will do the same today. Success rate has been around for awhile – The Hidden Game of Football wrote about it in the late ’80s and Football Outsiders has been tracking it for close to a decade. Everyone has their own unique definition, it seems; here is mine.

C.J. Spiller is a success.

• I started with every play from scrimmage where a running back was credited with a carry. I then removed all instances of 3rd or 4th down carries where the back needed to gain more than 5 yards for a first down, since the primary goal in these situations usually isn’t to get the first down. However, on the rare occasions where a running back did convert for the first down, those plays were kept in the data set. This has only happened 20 times this season.
• On 3rd and 4th down, a success is a rush that gains a first down (or touchdown). A failure is every carry that does not result in a first down.
• On 2nd down, a success is achieved when the player gains at least 50% of the yards needed for the first down. This means that 2nd-and-8 runs are failures unless they pick up 4 yards; on 2nd-and-7, the running back must also gain at least 4 yards. A rush for one yard on 2nd-and-3 is a failure, and so on.
• On 1st down, a running back is credited with a successful carry if he gains at least 40% of the yards needed; therefore, four yards are required on 1st-and-10 before the running back is given credit. On 1st and goal from the 5, a two-yard gain would be considered a success.

The league average success rate by these rules is 49.8%. The table below lists all running backs with at least 50 carries, along with their number of rushes (which excludes the excluded carries), number of successful runs, and their success rate. The table is sorted by the far right column, which shows how many successes over 50% of their runs the player had. In the event of a tie, the player with more carries was ranked higher.
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