Each of those Underwood teams averaged at least 76 points and were ranked in Ken Pomeroy's top 60 for offensive efficiency. Last season's Cowboys ranked first in that category and fifth in the nation with 85.7 points per game.
So what is this offense? And what makes it so effective?
Underwood, whom the Illini hired in March, has tinkered with the system for more than 20 years. It contains elements of the system Johnny Orr ran at Iowa State in the 1980s, Tex Winter's triangle offense he ran at Kansas State and later as a Bulls assistant and Dana Altman's spread system he used at Creighton in the 1990s.
Underwood began running some basic spread offense sets when he was an assistant at Western Illinois from 1992 to 2003. When he was hired at Daytona Beach (Fla.) Community College in 2003, his second stint as a junior-college head coach, Underwood said he really started experimenting.
The system isn't easily implemented. But if used correctly, it can give defenses fits, especially as opposing coaches try to scout and prepare for it.
The offense is about "constantly attacking the rim," Underwood said, either through dribble penetration, precise passing or cutting. The scheme draws defenses away from the basket.
"In essence, it's ball movement and player movement, and that happens simultaneously," Underwood said.
The offense uses players interchangeably at various positions, not determined by height, to create mismatches, typically with four guards on the perimeter and a big man -- who in the past hasn't been all that big -- in the high post. Underwood said he could use 6-foot-4 freshman guard Mark Smith at the five position for Illinois.
"I always bought into the concept of putting five good players on the floor no matter what size they are," Underwood said. "I never understood why people were enamored with a 7-foot center who wasn't any good, just because he was big."
Action begins with the ball reversed to the wing to initiate the offense. Usually, it starts with a player cutting to the rim for a possible layup. If he isn't open to score, he cuts to the corner.