KIEREN Jack personified Sydney's early-season struggles, but now that the perennial contenders are back amongst the premiership race, he's the poster boy for their stunning turnaround. 

While the Swans' 2017 campaign started disastrously and their finals hopes looked to be disappearing with every loss, Jack was out of form and having little impact in his new role as a permanent forward.

Critics began to circle and some predicted the demise of the former club champion, All Australian, and 2012 premiership midfielder, after he'd averaged just 15.8 possessions in his first five games, his worst return since 2009, and kicked just three goals.

But what those outside the walls of the Bloods didn't know was that Jack was battling painful tendinitis and inflammation in his left hip, the same issue that saw him to miss the entire JLT Community Series.

He managed to get himself up for the season opener and was solid against Port Adelaide, but his strength and fitness slowly dropped away, until the Swans' coaching staff decided enough was enough after another poor showing against Greater Western Sydney in round five.

"You think at the time that you're fit and healthy, and mentally you fight yourself about it, but the reality was that I wasn't," Jack told AFL.com.au this week. 

"You get caught up in a cycle; you don't train early in the week to get yourself right for the game, do a bit later in the week, then pull up sore from that, and then you can't do what you need to do in the game, and you're even worse for the following week.

"I was frustrated and not happy with the way I was playing, so in the end we decided to take some time off and get the injury right.

"Although I'm not a big guy, my strength as a player has always been my power around the ball, my footwork, and being able to get in and out of packs, and my body just wasn't allowing me to do what I wanted to do at the start of the year."

With fellow former skipper Jarrad McVeigh, Dane Rampe, Isaac Heeney, Gary Rohan, and Tom Papley all missing with injuries and illness, Jack said he felt a responsibility to his team to take the field early in the season.

"It was certainly a factor," he said.

"Where we were as a team at the start of the year we were lacking some leadership, we had some new players in the team, especially in the forward line. 

"But in the end I just wasn't being productive enough for the team so we decided to take a break." 

Jack returned to the senior team in round 13 against the Western Bulldogs and while he's now managed six games in a row, it's his past three that have been most impressive. 

The 30-year-old has gathered over 22 disposals in wins over Melbourne, Gold Coast and the Giants, laid 25 tackles, and spent more time in the midfield where his power running has been on display. 

The early-season media criticism has turned to praise for the three-time Brett Kirk medallist. Not that he has any issues with whatever spotlight comes his way. 

"If you put yourself out on the field you open yourself up to criticism and that’s fine," he said.

"These days there's so many journalists and so much coverage that you're bound to come across it at some stage, but as a player you can do two things. 

"You can buy into it and read it and start believing it, or you get back to it, work hard and get yourself back. 

"As an older player I'm well equipped to deal with all that, but I think the landscape now for a young player coming in would be pretty tough. 

"With all the eyes on you and scrutiny, and the amount of journalists writing about the game and looking for content to write about, it would be an emotional rollercoaster."