2007-08: Patrick Killeen was forced into the starting role for the Brampton Battalion early on in the season due to injuries and later split the duties with Bryan Pitton. He posted 20 wins in 34 games and a .908 save percentage. Killeen was chosen by the Pittsburgh Penguins in the sixth round, 180th overall, of the 2008 NHL Draft.
2008-09: Killeen split starting duties with Brandon Foote and Thomas McCollum, managing a 19-11-2 record, a 2.85 GAA, and a .888 save percentage.
2009-10: Killeen started 63 games for Brampton in his third full season with the OHL club and posted a 23-25-13 record, a .913 save percentage, a 2.42 GAA, and 5 shutouts. The Battalion reached the second round of the playoffs after finishing third in the Central Division and in 11 playoff games Killeen was 4-7 with a 3.44 GAA and .887 save percentage.
2010-11: Killeen made two relief appearances for AHL Scranton/Wilkes-Barre and spent the bulk of his first pro season in the ECHL. He stopped 6 of 8 shots in just under 19 minutes of AHL action. In 40 games with ECHL Wheeling, he was 19-18 while managing a 2.87 GAA and .901 save percentage. Killeen was 1-2 with a 2.68 GAA and .883 save percentage in three playoff games for the Nailers. Killeen was selected for the ECHL All-Star Game – stopping 7 of 8 shots in his one period of action.
2011-12: Killeen appeared in five games for Penguins AHL affiliate Wilkes-Barre/Scranton, spending most of his second pro season with the ECHL's Wheeling Nailers. He was 2-2 with a 2.93 goals against and .871 save percentage in AHL action. Killeen and Avalanche prospect Peter Delmas split the ice time for the Nailers. He was 19-16 with four losses coming in overtime and had two shutouts with a 2.69 goals against and .893 save percentage. Killeen started all four playoff games in the series with Kalamazoo and was 1-3 with a 3.54 goals against and .864 save percentage.
Killeen has good size at 6'4 and is good at taking out the bottom half of the net. A hybrid style goaltender, Killeen relies on his size and reflexes. He also has fairly good lateral movement is capable of making second and third saves if need be.
Like most young goaltenders Killeen needs to further simplify his game and become squarer on the puck. While he is able to flop on the ice fairly well, he is a more effective goaltender when he remains calm and upright.
Killeen will likely play the bulk of his starts in 2012-13 for the Penguins ECHL affiliate.
Killeen was dealt by the Pittsburgh Penguins to the Columbus Blue Jackets at the 2013 NHL trade deadline.