2010-11: Tierney struggled in his rookie OHL season with the London Knights where he scored only three goals along with eight assists and a poor minus ten rating in just 47 games. The Knights lost 4-2 in their first round series against the Owen Sound Attack and the rookie only contributed an assist in four games.
2011-12: Tierney had an good second year in the OHL with the London Knights where he played more games and improved his previous season's offensive numbers by 23 points in his draft year. The two-way centerman scored 11 goals (two shorthanded) along with 23 assists and an excellent plus 25 rating while playing the shutdown against the opposition's best in 65 games. Tierney and his Knights lost in over-time of the 2012 Memorial Cup finals against Shawinigan after beating the talented Niagara Ice Dogs 4-1 in the OHL finals for the Roger Championship to get to the Memorial Cup tournament. The young Knights team put together a good playoff run of 16 wins with only three losses on their way to winning the OHL championship. The big centerman also contributed five goals (one shorthanded) along with two assists and had a plus one rating in 19 playoff games.
Tierney has the potential to be a high-end playmaker, is already an excellent penalty killer, has good hockey sense and brings a good work ethic to every shift. The solid two-way centerman, like all young prospects needs to add more strength while continuing to improve his overall game and needs a quicker, harder shot.
Tierney will have time to develop on a good young London Knights team over the next two years at the junior level. The physical centerman has more offensive potential when given more opportunities to play bigger minutes this upcoming season in the OHL.