Leslie could not win more than one match in any event during the 2013–14 season. He did reach the second round of a ranking event for the first time in his career at the UK Championship by coming back from 4–0 down against Jack Lisowski to win 6–4, a performance he described as the best of his career so far, but he then lost 6–3 against Liang Wenbo in the next round.[6][7] Leslie was beaten 10–6 by amateur player Christopher Keogan in the opening round of World Championship qualifying. He was relegated from the main tour as he ended the season ranked world number 101, well outside of the top 64 who remain.[8] Leslie played in the 2014 Q School to try and win his spot back and succeeded in the second event by defeating Eden Sharav in his final match to earn a new two-year tour card for the 2014–15 and 2015–16 seasons.[9]
2014/2015 season
In the qualifying rounds of the 2014 Australian Goldfields Open, Leslie beat Hammad Miah 5–4 and Sam Baird 5–3 to play in the final round, but was narrowly eliminated 5–4 by Marcus Campbell.[10] Later in the season after losing eight matches in a row, Leslie recorded the result of his career to date by defeating Mark Allen, a player ranked 106 places above him in the rankings, 5–1 to qualify for the China Open.[11] There, he reached the last 32 of a ranking event for the first time with a 5–1 victory over Joe O'Connor, but was thrashed 5–0 by Mark Williams.[10]
2015/2016 season
A disappointing season saw Leslie fail to qualify for any ranking event other than the UK Championship and Welsh Open, for which he gained automatic entry and he failed to pick up a frame in either of those as he lost in the first round to Gerard Greene and Judd Trump.[12] He finished the season 94th in the world rankings and therefore fell off the snooker tour.[13]