College Baseball First Team All-American. He was selected by the Chicago Cubs in the ninth round of the 2002 Major League Baseball Draft. Minor leagues (2002–2005) In 2002, Greenberg hit .224 for the Lansing Lugnuts, and .384/.500/.575 in 21 games for the Daytona Cubs, swiping 15 bases in 17 tries. Greenberg spent the 2003 season with Daytona and put up a .299/.387/.410 line, stealing 26 bases in 35 attempts. In 2003, when Executive Editor of Baseball America Jim Callis was asked whether he thought Greenberg had a chance to be a starter, or was destined to be a backup, he responded: "Very good character guy, often compared to John Cangelosi, more of a fourth or fifth outfielder." In 2004, Greenberg hit .291 with a .381 OBP for Daytona, with 12 triples in 91 games (tying for the Florida State League lead), and moved up to the West Tenn Diamond Jaxx, where he put up a .274 batting average in 33 games. His season ended with the Iowa Cubs. Overall, his 14 triples tied him for third in the minor leagues. Greenberg began 2005 with West Tennessee, hitting .269 with a .386 on-base percentage with nine triples and 15 steals. He spent three months of the winter playing baseball in Venezuela, playing center field and leading off. Chicago Cubs (2005) On July 7, 2005, Greenberg was called up to the Cubs' major league team from their West Tennessee Double-A affiliate. Pinch hitting in the ninth inning against the Florida Marlins, in a game on July 9, Greenberg was hit directly in the back of his head by a 92 mph fastball on the very first pitch from Valerio de los Santos. Greenberg suffered a concussion as a result of the beaning, and was immediately removed from the game and taken to a hospital. Carlos Zambrano was sent in to pinch-run for Greenberg, and eventually came around to score the Cubs' fifth run in an 8–2 victory. De los Santos called to check on him and apologize. As a result of the injury, Greenberg couldn’t sleep upright, or even bend down to tie his shoes without losing his balance. He spent the rest of the 2005 season on the 15-day disabled list, and continued to suffer from positional vertigo, terrible headaches, nausea, double vision and dizziness. Return to minors, Independent League (2006–2011) In 2006, Greenberg hit .179 for the Diamond Jaxx and