In February 2005 Grabow signed a contract pursuant to which he would make $327,000 in the majors, but $240,000 if he pitched at Class AAA Indianapolis. He was a workhorse in the Pittsburgh bullpen in 2005, appearing in 63 games in his second full major league season. He held opposing batters to a .186 batting average and a .186 slugging percentage when there were runners in scoring position. He stranded a major-league best 89.7% of his inherited runners, allowing just 4 of 39 inherited runners to score.