Last post, we looked at the change in rushing and passing defense productivity from one year to the next and used this as an example of regression toward the mean. ie if a variable lies far from its true value in the first measurement, the second measurement will tend to be closer to the true mean. In this evaluation, we are assuming that the true mean is represented by the mean of all teams over the course of the past 14 seasons, which may not be entirely representative of a given team, but is well distributed for the whole of the NFL. The true mean of a given team in a given year will depend on individual players, player interactions, and coaching quality, yet the productivity of a defense in a year describes ~35% of the variance in the change in productivity observed in the following year. This is regression towards the league average.

Let’s make this same analysis with team offense productivity, looking at rushing and passing separately. We will use the same point system that we used for defenses (largely based on YDs and TDs with standard fantasy scoring) and apply the same Johnson transformation to normalize the data. We will apply the same simple subtraction of a year’s FPs from the previous years to represent the yearly change in production that we did with the defense.

Histograms of this data show a normal distribution in the yearly change of both rushing and passing productivity. The mean yearly change is an ever so slight improvement for both rushing (0.03 FP/game) and passing (~0.2 FP/game). The greater yearly improvement in passing productivity is reflective of the league-wide increase in average yearly passing production that we discussed in the first post.

Once we have the yearly change, we can look at how this change correlates with the success of the previous year.

Just like defenses, highly successful offenses are more likely to be less successful the following year and lousy defenses are more likely to improve. With offenses, however, past success is less predictive of the variance observed in the year-to-year change than we saw with the defenses. This is particularly true of passing production, as only ~23% of the variability is accounted for by the past year’s performance. This suggests that particularly with passing offense, other factors are more important.

Like we did with the defenses, let’s look at a sampling of the outliers.

Rushing:

Major Drop-offs:

Truly horrendous rushing teams have always improved or stayed nearly the same. They rarely get worse. (This was true of defenses too. Keep this in mind when analysts claim that the Cowboys defense will be even worse this year as a reason for hyping Tony Romo.)

Detroit 2005 to 2006 (Bad to Worse): SoS was easier in 2006. Head Coach change (Mariucci to Marinelli). Offensive Coordinator changed from Greg Olson to Mike Martz. Martz came from a head coach position in St. Louis, which had been ranked top 5 in the league in passing yds for all 7 years that he was there. For the two years that Martz was offensive coordinator in Detroit, the lions were in the top 10 for passing yds. No doubt, Martz brought a focus on the pass, at the expense of the run, to Detroit. This may have been in part due to a sophomore slump by RB Kevin Jones in the 2005 season. Starting QB in 2006 was Kitna, which brought an end to the Joey Harrington era. There were changes in the starters of the offensive line at LG and RT. Neither new player played in the NFL after the 2006 season. Kevin Jones would play a couple more years in the NFL, one more year in Detroit and a year in Chicago. The first round draft pick never returned to the success of his rookie season. The drop-off is most likely attributable to the Martz offense.

Arizona 2004 to 2005 (Average to Bad): SoS was easier in 2005. New rookie offensive coordinator (Keith Rowen). 35-yr-old Emmitt Smith retired after the 2004 season and was replaced with uninspiring Marcel Shipp. This was also Kurt Warner’s first year in AZ, replacing omnipresent Josh McCown. The drop-off was most likely due to a combination of the loss of a hall-of-famer RB (who was productive, even if he was old), a pass happy OC (AZ led the league in pass attempts in 2005), and replacement of half of the offensive line with inexperienced players.

Kansas City 2006 to 2007 (Good to Bad): SoS was easier in 2007. No coaching changes of note. The main thing here is that Larry Johnson suffered a season ending foot injury in week 9 of 2007. This left KC in the lurch and ended up relying much more on the pass. They went from 3rd in the NFL in rush attempts in 2006, to 30th in 2007 and 27th in pass attempts to 11th.

Major Improvements:

San Diego 2005 to 2006 (Good to Great): This is the height of Tomlinson’s greatness. SoS was more difficult in 2006. Coaching staff was same, though OL assistant Hal Hunter was added in 2006. 2006 was the first year the Philip Rivers became a starter, replacing Drew Brees. Replacement of the LT with two time pro-bowler Marcus McNeill was the only other change in the starting offensive line-up. Improvement is likely attributable to the incredible success of LT and the reluctance to rely on unproven Rivers (pass attempt ranking dropped from 13th in 2005 to 25th in 2006).

Minnesota 2001 to 2002 (Bad to Good): SoS was more difficult in 2002. Head coach Scott Tice was sacked during the 2001 season and Mike Tice took the reins for the final game and all of 2002. Tice installed his own coordinators, including OC Scott Linehan. Linehan’s offense is usually seen as being pass oriented (look at what he’s doing in Detroit), but in his first two seasons in the league, both in Minnesota, his offense ranked in the top 10 for running attempts and led the league in rushing yds in 2002. Under Linehan, Sophomore RB Michael Bennett became a Pro Bowler in 2002. With only the LT changing in the offensive line, it seems like most of the improvement here was the installation of a competent coaching staff that could unleash their players’ talents.

Washington 2011 to 2012 (Bad to Good): SoS was more difficult in 2012. No coaching changes, deep into the Mike Shanahan era. In 2011, Washington lacked a consistent starter with Evan Royster, Roy Helu, Tim Hightower, and Ryan Torain all opening games. 2012 saw the start of RGIII’s NFL career. Perhaps because of the installation of the rookie QB, OC Kyle Shanahan’s play calling reversed course from his history of favoring the pass and in 2012, Washington ranked 3rd in the NFL in rushing attempts, and only 30th in pass attempts. Aside from the change in QB, the offensive line was more stable in 2012, particularly on the left side, with the return of Pro Bowler Trent Williams from a 4 game suspension in 2011 due to failure of league drug tests. So improvement this year seems to be improvement in OL and OC play calling that may have been driven by reliance on a rookie QB.

Carolina 2007 to 2008 (Bad to Good): SoS was easier in 2008. Coaching staff was unchanged. The O-Line was much improved, with 4 of the 5 regular starting O-lineman being replaced from 2007 to 2008. Sophomore RB DeAngelo Williams had a breakout year behind this O-Line.

Passing:

Major Drop-offs:

San Francisco 2004 to 2005 (Bad to Worse): SoS was easier in 2005. Complete coaching staff overhaul. Rookie Alex Smith became the starting QB for most games in 2005. All Tackles in the OL were replaced from 2004 to 2005.

Oakland 2005 to 2006 (Average to Bad): SoS was more difficult in 2006. Change in head coach and OC. Starting RB Lamont Jordan tore his MCL in game 10 of the 2006 season. Little consistency in OL from 2005 to 2006.

Minnesota 2004 to 2005 (Great to Average): SoS easier in 2005. OC Scott Linehan was replaced with Steve Loney. Never heard of him? It was his one and only season as an OC in the NFL. QB Dante Culpepper, coming off of a Pro Bowl season, was replaced with Brad Johnson after Culpepper sustained a season ending knee injury in late October. Significant changes in the starting O-Line, including the loss of Pro Bowler Center Matt Birk for the entire 2005 season to a hip injury.

Major Improvements:

Denver 2012 to 2013 (Great to Record-Breaking Amazing): SoS in 2013 was comparable to 2012. Change in OC. Two members of the O-Line were replaced (Though Peyton Manning is basiccally his own OC). One of the replacements played at an all-pro level in 2013 (Louis Vasquez), in addition to the pro bowl talent they had the previous year (G Zane Beadles, all-pro T Ryan Clady). Receiving corps was also improved (Wes Welker replaced Brandon Stokley, Julius Thomas replaced Joel Dreesen). It was just a perfect storm of improvements.

New England 2006 to 2007 (Average to Great): Randy Moss came to New England by way of Oakland. Wes Welker also arrived in New England from Miami. Based on this and Tom Brady’s performance last year, Brady seems pretty dependent on having a high quality receiving corps.

Denver 2011 to 2012 (Bad to Great): It’s not surprising that Denver has made two major step changes upwards since 2011. The SoS was more difficult in 2012 as compared with 2011, but Denver’s leading passer in 2011 (Tim Tebow) was replaced by future hall-of-famer Peyton Manning.

Takeaways

1. Strength of schedule seems to be a terrible predictor of major changes in offensive productivity.

2. Loss of truly exceptional talent at any position can have a dramatic impact on offensive productivity.

3. Losses in the offensive line should not be discounted. A poor O-line can cripple a rushing game and lead to hurried and inaccurate passing.

4. Offensive coordinators with known track records may impact their new teams in predictable ways. Unknown OCs or OCs coming up from college level seem to be a crap shoot. I’ll try to look more closely at this in a future post.

5. Passing performance seems most dependent on QB ability (ie, Peyton’s move to Denver), but can also be decimated by a poor or injured receiving corps (ie, Brady’s improvement in 2007 and drop-off in 2013).