Gersbach was handed his A-League debut from the bench against Melbourne City in round one of last season's A-League - as a 17-year-old schoolboy.
Shortly after, he became a regular starter at left-back, but with the finals in sight and his dream of winning a championship in his first season within reach, he lost his place in the starting side.
The Sky Blues defender spent most of the time on the bench, without being used in the last few rounds of the regular season, with Nikola Petkovic at left-back, but worse was to come for him.
He wasn't included in the 17-man match-day squad for the semi-final against Adelaide United, which was played one day after his 18th birthday and which Sydney won, 4-1.
The following week, he was left out for the grand final, in which Sydney went down 3-0 to Melbourne Victory.
Gersbach admits it was tough to take.
"It was disappointing," he said. "I would've loved to have been involved in that game against Adelaide and obviously the grand final. It would've been a massive occasion, but there's not much you can do about it apart from work harder and make sure it doesn't happen again."
The 18 year-old said coach Grahm Arnold explained in detail to him why he had initially been put back to the bench.
"Arnie' said he felt my form had dropped off a bit and that he thought there was a bit of fatigue showing as well, at the end of a long season," Gersbach said. "Nikola came in and did well at left back, so it was hard for me to get back in.
"I felt alright, to be honest, so it was a bit of a surprise. I didn't think my form had dropped too much, but it was the week that Jacques Faty returned from injury and Matty Jurman was doing really well, so I got squeezed out when Nikola was moved from centre-back.
"But you've always got to respect the decision of the coach. That's football - your place in the team is never certain."
Petkovic left the club at the end of last season, but Arnold signed left-back Riley Woodcock from Perth Glory. The coach wants strong competition for every place in the team.
"Arnie signed Riley Woodcock, so there is competition for places. Everyone gets their chance to push for a spot. There's no certain starter or anything, so we have to prove ourselves in training and the pre-season trial games we've got left as well.
"I'm sure whoever deserves the left-back spot at the start of the season will get it. We'll see what happens. All I can do is give it my best shot - train hard and make sure my form is good whenever I play.
