The Shamrock Rovers star is to take an indefinite break from football.
The Irishman scored goals for fun in the competition, finishing as second-top goalscorer with six goals in a competition that also featured the likes of Ajax’s Viktor Fisher, Tottenham’s Alex Pritchard and Barcelona’s Sandro.
Drennan looked like being a potential star of the future at Aston Villa but it never happened. Instead he headed back to his native Ireland in 2015, joining Shamrock Rovers.
The move shocked many Villa fans but this week’s revelations have painted a picture behind the reasons why he made the move home.
Drennan announced this week he would be taking an indefinite break from playing the game, as he is suffering with depression.
He is quoted by the Irish Mirror as stating:
“Maybe I should have got the help earlier but I'm getting the help I need now and hopefully I get back on track.
"I'm trying to get help and back to feeling normal, as they say - more in a positive place instead of always thinking negatively."
He also suggested his move to Villa at such a young age was when his illness started:
“It's been about three years, maybe even longer, that I've noticed I haven't been right in the head.
“It's been tough. I've had ups and downs and I thought coming home from England would be a big help but I don't think it was.
“It all started over in England, going away when I was younger and feeling this way. There's nothing to do outside of the football.
“I was 15 and there's only so much to do when you're that age. You're limited to what you can do.”
Drennan’s decision to speak so openly about his mental health problem must be applauded and respected.
He has now headed home to Kilkenny and will be playing hurling in order to keep fit.
The former Aston Villa star is very brave to discuss the issue so candidly and there is no doubt that most Aston Villa fans will be wishing their former protégé all the best in his recovery.