Hummel led the "Baby Boilers", along with Chris Kramer, JaJuan Johnson, Keaton Grant, and E'Twaun Moore, to a second-place finish in conference play and on to a second-round NCAA tournament appearance, where they lost to a senior-led Xavier team.

He broke the school freshman record with a 44.7 three-point field goal percentage, while leading the Big Ten Conference.

He also recorded the highest free throw percentage for a freshman in school history with 86.5 percent accuracy, which led the team, and broke Kyle Macy's 33-year-old .859 mark.

As one of three tri-captains on the team and named the Preseason Big Ten Player of the Year, he scored his 500th career point on December 13, 2008, against Indiana State.

He won back-to-back Big Ten Player of the Week honors in the month of December, pulling down a career-high 14 rebounds and scoring 25 points during that time frame.

Hummel began battling with back spasms and a broken vertebra, which forced him to sit out five games and kept him from practice involvement.

Although having dealt with performance affecting injuries and missing four conference games, he was named a Third Team-All Big Ten selection.

[1] To start the 2009–10 season, Hummel was picked as one of fifty players as a preseason John R. Wooden Award candidate, along with teammate, E'Twaun Moore.

He tied his former assistant coach, Cuonzo Martin's single-game school record of 8 three-point field goals made in a losing effort against an Evan Turner-led Ohio State team on January 12, 2010, in which he also scored a career high 35 points and received a dislocated pinky finger.

In his team's tenth straight win in conference play at Minnesota on February 24, Hummel injured his right knee in the first half after he slipped while attempting to plant his foot.

Purdue officials reported the following day that Hummel tore his anterior cruciate ligament (ACL) and would miss the rest of the season.

On November 11, the Preseason All-Big Ten selection scored 21 points, making 5-of-7 beyond the arc to open the season against Northern Illinois in 20 minutes of play.

On December 3 in a three-point loss at #11 Xavier, Hummel suffered from cramps and dehydration, which eventually caused him to fall to the floor in the last minute of the game.

In his last game at Mackey Arena on February 29, Hummel recorded a career-high 6 assists, along with 26 points and 8 rebounds against Penn State.

[1] Hummel became the 44th player in school history to score over 1,000 career points, surpassing the mark with a 13-point performance during a 73–66 loss on January 9, 2010.

[18] With his lower back injury healing daily, Hummel was selected for the USA Men's 2009 World University Games in Belgrade, Serbia under Wisconsin head coach Bo Ryan.

[19] Along with the likes of fellow Big Ten players Evan Turner and Talor Battle, Hummel helped lead Team USA to the Bronze medal against Israel, finishing with a 6–1 record.

On October 4, 2017, Hummel announced he was retiring from professional basketball in order to become a studio analyst and color commentator for ESPN and Big Ten Network.