A week ago I compiled the main USC offense stats for the Pete Carroll era and their respective trends. Here as a follow up is the defensive side of the ball and how USC has generally performed. All data is either from the NCAA website or the USC football website. As a reminder the 2006 season stats are skewed due to the shorter game that season which resulted from a change in play clock rules. Bump all those figures up by about 10% and you'll probably have a more accurate assessment of that defense when comparing it to other years.
For starters here is the basic trend for the USC rush defense in terms of yards per game. The worst season was Pete Carroll's first back in 2001 at 149.2 yards per game followed by the 2005 defense that allowed 130.5 yards per game rushing. The best seasons were the 2003 and 2004 squads which allowed 60.2 and 79.4 yards per game respectively. For most of 2007 the Trojan defense was on track to challenge the 2003 squad in this dimension however three games stopped it from reaching that lofty level (Oregon 182 yards, Cal 200 yards, Illinois 144 yards allowed rushing). In terms of rush yards per carry you can see the same basic trend is exhibited below. Keep in mind also that the NCAA takes sack yards off the running game totals so years that have high sack totals are of course aided in this dimension. In 2003 for example the 55 sacks took 415 yards off the actual rush total. In 2005 the figure was for comparison was 193 yards on 32 sacks. The 45 sacks recorded this past season subtracted 298 yards off the rushing totals.
Moving onto pass defense first here is the overall trend for yards allowed per game. The high mark in terms of defense was the 2001 squad in Pete Carroll's first season while this year was the best since that year. The low point in passing yards allowed per game was the 2003 season where 276.2 yards were surrendered. Keep in mind that 2003 was also the season where the USC rush defense was at its peak and teams may have opted to throw more as a result.
In terms of completion percentage allowed you can see the number varies from as low as 49.8% to as high as 59.7% allowed overall. A word of caution is of course in order when comparing teams. The leading teams in the NCAA often allow less than 150 yards passing per game and a completion percentage of 45%. However the leading teams in this dimension often play in conferences that do not have passing attacks as sophisticated as the Pac-10 I suspect. As an example in 2005 LSU had the 11th ranked pass defense in the nation. That season they played a game at Arizona State where Sam Keller completed 35 of 56 passes for 469 yards versus the Tigers. The Trojans that same season ranked 73rd in the nation in passing yards allowed. When USC faced Sam Keller at ASU in 2005 he completed 26 of 45 passes for 347 yards. The LSU pass defense for example may have indeed been better than USC's which was racked by injuries that year. However when facing a common opponent the numbers were not all that different and actually slightly worse.
In terms of Yards Per Attempts (YPA) and Yards Per Completion (YPC) the trends for USC are more stable than the passing yards allowed. The ranges vary much less with a low of 5.5 YPA and 10.2 YPC this season against a high of 6.6 YPA in 2005 and 11.6 YPC in 2002.
Here is USC's overall performance in terms of 3rd down defense. As you can see below this was USC's 3rd best performance on defense the past seven years allowing first downs on average 31.0% of the time on 3rd down. With this statistic you can see why coaches often opt to force the offense to try to march the length of the field on them. Odds are that not too many drives will be sustained when conversion rates are only in the 30% range in general.
The trend for turnovers forced by USC is unfortunately not very positive the past two years althought is year showed improvement from 2006. The big drop off has been in interceptions for the most part although fumbles forced were down last season as well. This stat actually has some profound implications for scoring on offense which I will explain later in another post. The high point for USC in terms of turnovers forced was 42 in 2003 the low point was just 22 in 2006. Putting that in perspective teams average about 180 drives over the entire season. Between 2001 and 2005 USC averaged a takeaway 38 times per season or roughly one on every fifth drive...That figure has now slipped down to an average of 25 times per season (the last two years) or a turnover forced in just one of every seven drives. In effect the opposition is getting to continue about 13 more drives over the course of a year (roughly one entire game) keeping the Trojan defense on the field longer. In addition is the equally important effect on field position. When USC forces a turnover on defense the average field position for the Trojan offense is the opponents 40 yard line. From there USC is 70% likely to score. When the opponent punts instead USC normally starts back on its own 20 yard line or worse. From there the probability of scoring dives down to a much lower figure.
On a more promising note the USC defense generated 45 sacks this past year for the third highest total of the Pete Carroll era. The trend picked up nicely in the second half of the season. Starting seniors Sedrick Ellis and Lawrence Jackson depart however taking away 19 of those 45 sacks. Replacing that output will no doubt be difficult but MLB Rey Maualuga (6 Sacks), Everson Griffen (5.5 Sacks) return in addition to Kyle Moore (2.0 Sacks) and a variety of other players (Brian Cushing, Fili Moala, Kaluka Maiava, Kevin Ellison, etc.) that each generated 2 sacks each as well. The Tackles for Loss (TFL) trend rebounded further this year as well but still was only the 4th best of the Pete Carroll era.
In terms of total yardage and scoring defense the trends were as follows. In 2007 USC actually allowed the fewest total yards of the Pete Carroll era edging out the 2004 squad by six yards. The worst USC defense in terms of total yards surrendered was the 2005 squad that was racked by injuries much of the year.
Scoring wise the USC defense has been fairly consistent allowing between 13 to 18 points per game overall. The 2005 squad once again was the weakest for USC allowing 22.8 points per game. This past season was the 3rd best mark of the Pete Carroll era allowing 16.0 points per game and raking 2nd in the nation behind Ohio State University.
Looking forward 2008 should be another good year on defense for USC. Departing seniors on defense include Terrell Thomas, Sedrick Ellis, Keith Rivers, and Lawrence Jackson. Key back ups graduating include Thomas Williams, Alex Morrow. Defensive back Mozique McCurtis has elected to concetrate on law school. Returning next season from injury are Josh Pinkard and Kevin Thomas in the secondary. USC should be set in the back seven with both talent and depth at LB and DB. Bigger questions exist for the front four where Averill Spicer and Everson Griffen will have the full time challenge of filling the big shoes of Sedrick Ellis and Lawrence Jackson. Previous recruits such as Christian Tupou, Da'John Harris, Derrick Simmons, and Trey Henderson will need to develop as well in the event of injury.