An average season at age 25 did not bode well for his chances as a prospect, but he parlayed an invitation to spring training with the Red Sox in 2001 into a spot on the big-league team for opening day.

However, he retained his spot on the roster for 2002, and responded with a much better season, hitting 20 home runs with a .330 on-base percentage and a .459 slugging average.

He finished the season with a combined .280 batting average and career highs in RBIs (97) and home runs (20), including a three-homer game with the Diamondbacks in July.

In 2005, his first year with the Blue Jays, Hillenbrand hit .291 with 18 home runs and 82 RBIs over 152 games, while splitting time between 1B, 3B, and DH.

[1] On July 19, 2006, Hillenbrand criticized the Blue Jays organization for failing to congratulate him on his recent adoption of a baby girl and not playing him upon his return.

After his playing career was over, Hillenbrand said he owed Gibbons an apology, while discussing his own mental problems he had suffered as a player.

"[6] On July 9, having been replaced by the emergence of Reggie Willits and first baseman Casey Kotchman, Hillenbrand was waived by the Angels.

On July 2, 2008, the York Revolution of the independent Atlantic League announced that they had signed Hillenbrand to be their starting third baseman.

[7] Hillenbrand played in 36 games for the Revolution, hitting .340 with two home runs and 25 RBIs before his season was ended by a hamstring injury.

[8] Hillenbrand returned briefly to baseball after a four-year layoff, playing for the Bridgeport Bluefish of the independent Atlantic League during the 2012 season.

"[12] In a text chat with baseball fans on the MLB Trade Rumors site on January 28, 2022, Hillenbrand talked about changing his life after the problems and deep unhappiness he had while being a major league ballplayer.