FEI Week 2: Defense Carries Hawkeyes
Iowa owns the nation's fourth-longest winning streak at eight games, including a smothering 34-6 victory over Indiana in Week 1 and another impressive 27-17 conquest over non-conference rival Iowa State on Saturday. Thus far, the Hawkeyes have mastered a particularly lethal combination of defense and special teams to dominate field position and seize short-field scoring opportunities. The Cyclones started four of their first nine possessions against the Hawkeyes from at or inside their own 10-yard line, each of which followed an Iowa punt and none of which ever advanced more than 14 yards downfield. Iowa scored two of its three touchdowns on the ensuing possession after pinning Iowa State deep—a short-field drive following a Brock Purdy interception and a fumble return touchdown early in the second half to open up a 21-10 lead.
Iowa's offense has sputtered itself this season, but it has not been pressured to produce much firepower either. Iowa mustered up only 11 first downs and 173 total yards on offense against Iowa State, and only 303 yards one week earlier against Indiana. No matter; the Hawkeyes defense has scored almost as many touchdowns through two games (three) as its offense (four). As we discussed a couple of weeks ago, defense and special teams touchdowns can have a huge impact on game results, but they are not useful data points in projecting future outcomes. Iowa's good fortune has been timely, but it is not likely to be a sustainable strategy for the season.
Consider also that the Hawkeyes were outpaced by the Cyclones by 2.02 net yards per play in the game. There are no specific statistical thresholds that guarantee victory, but dominant net yards per play margins do correlate strongly with scoring margins. Since 2007, teams that had a net yards per play advantage of at least 2.0 in a game won 97% of those matchups. A team overcame a net yards per play deficit of at least 2.0 and went on to win the game by at least 10 points on only 17 occasions over the last 14 seasons. Iowa achieved that unusual distinction on Saturday. (Coincidentally, the last team to do it was Iowa State, in a 34-17 bowl victory over Oregon in January.)
Iowa started the season with a top-10 preseason projection in the FEI ratings, so their strong start in 2021 did not completely come out of nowhere. They are up to No. 5 overall in this week's rankings, an ascent attributable to their wins against decent opponents and to the less-than-impressive performances to date of teams they have passed along the way. I do not anticipate Iowa will ascend further, however, without finding more success on offense.
Over the last five seasons, the highest overall FEI rank at the end of the year for a team with a below-average offense was achieved by the 2016 Florida Gators (No. 20 overall, 9-4 against FBS opponents). On several occasions in the same span, the best overall ranking for a team with a below-average offense was outside the top 40. A dominant defense can win games, but it needs to be paired with an at least above average offense to be a legitimate conference or national contender. Iowa's offense so far this season ranks just below average in opponent-adjusted efficiency, and that rating is propped up somewhat by a slightly above average offensive rating projection to start the season. The Hawkeyes rank 98th in unadjusted offensive drive efficiency through two games.
They will have their opportunities to get the offense going soon—Kent State (125th in defensive FEI) and Colorado State (108th) are up next on the schedule before the Hawkeyes resume conference play against Maryland in October. Iowa will not need to change its defense-first identity entirely to make a run to a Big Ten conference championship, but they will need to turn more offensive possessions into scoring opportunities and not count on its defense to do it all.
2021 FEI Ratings (through Week 2)
FEI ratings (FEI) represent the per-possession scoring advantage each team would be expected to have on a neutral field against an average opponent. Offense ratings (OFEI) and defense ratings (DFEI) represent the per-possession scoring advantages for each team unit against an average opponent.
Preseason projected ratings are progressively phased out over the course of the season. Click here for expanded ratings for all teams. Ratings and supporting data are calculated from the results of non-garbage possessions in FBS vs. FBS games.