Entering his sophomore season, he was expected to be a key part of the starting pitching rotation. The 2003 season saw the development of Rice's "Big Three" rotation, featuring Humber and sophomore classmates Wade Townsend and Jeff Niemann. Humber developed a curveball that season, to augment his arsenal that included a fastball, changeup and split-finger fastball. During the season, Humber achieved his 17th consecutive win in WAC play. He was recognized as a Third Team All-American by Collegiate Baseball and was a First Team All-Western Athletic Conference honoree. The trio entered the 2003 College World Series with gaudy numbers — Niemann (16–0, 1.63 ERA) and Townsend (10–1, 1.90 ERA) complementing Humber — and with Humber scheduled for the third game, if necessary. Humber finished with an 11–3 win–loss record with a 3.30 ERA, as Rice won its first national championship in any team sport. He pitched a complete game in the decisive third game of the series, a 14–2 win over the Stanford Cardinal. The game established a College World Series record for largest title game margin of victory. During the season, Rice established a school record 30-game winning streak. Upon his becoming the College World Series hero, June 26, 2003 was declared 'Philip Humber Day' in his hometown of Carthage, Texas in his honor. Following the season, all three pitchers competed in collegiate summer baseball in the Cape Cod Baseball League; Humber pitched for the Yarmouth–Dennis Red Sox. "Baseball America" rated Humber as the seventh-best prospect in the Cape Cod League.