Nalen was a three-year startingoffensive lineman for Boston College, earning numerous honors that included third-team Associated PressAll-America, second-team All-Big East and first-team ECAC. He started every game from 1991 to 1993, serving as the long snapper, backup center and then starting center for the last three games in 1990. He redshirted in 1989. Nalen closed out his college career with appearances in the East–West Shrine and Senior Bowl games. In 1993, Nalen was an All-American honorable mention and All-Big East second-team pick by The Poor Man’s Guide to the NFL Draft. That year, Boston College ranked fourth in the nation in total offense (506.4 yards per game). Nalen's blocking was a key factor in the Eagles' 41–39 upset win over Notre Dame in South Bend, Indiana that season.
On January 6, 2009, Nalen announced his retirement from professional football after spending his entire career playing for the Denver Broncos. He was the last remaining player from the Broncos' Super Bowl titles in the late 90's.
In 2013, Nalen was named to the Broncos Ring of Fame.
Nalen is a co-host on 104.3 The Fan’s “The Drive” with Darren “DMac” McKee.