 Before reaching the major leagues, he umpired in the Appalachian League (1991), Florida Instructional League (1991 and 1994), South Atlantic League (1992), Florida State League (1993), Eastern League (1994–1995) and International League (1996–1999).During the 2005 NLCS, Gibson didn't see a ball hit off of Mark Grudzielanek's foot while he was still in the box, which would have been a foul ball.Instead, Grudzielanek grounded out to pitcher Roy Oswalt for the first out of the home half of second inning.