It was all so overwhelming for Oisin Mullin when he first considered playing Australian Rules football that he opted to stay put, sticking with the Gaelic Athletic Association (GAA) and putting off his far-flung dream.
Geelong had shown strong interest in the half-back following his pivotal role in County Mayo reaching back-to-back All-Ireland Senior Football Championship finals in 2020 and 2021.
The prospect of moving away from his friends and family amid the COVID-19 global pandemic to play a sport he had minimal experience in, however, was too heavy a decision to commit to.
"With COVID and everything, it made things slightly awkward getting visas sorted," Mullin told media on Wednesday.
"I would have been delayed getting over until mid-February (in 2022), and in my head, I thought I'd be too far behind at that stage.
"You don't really know what you're coming into. It was just a bit overwhelming at the time, so I ended up not coming."
The Cats would offer one of the GAA's brightest young stars another opportunity following their premiership season, and this time, Mullin didn't hesitate, training with the Cats as a Category B rookie ahead of the 2023 season.
Since then, Mullin's progress has been exponential, debuting in Round 9 of the 2023 season, where he'd ultimately play six games. In 2024, he'd feature in 12 games for Geelong, including both of their finals matches, and has missed out on just one senior game in 2025.
His growth in the foreign game came to a head in the Second Qualifying Final, finally kicking his first AFL goal after nine previously unsuccessful attempts.
It couldn't have happened on a grander stage, in front of the raucous MCG grandstands filled with over 86,000 fans, the bulk of whom were supporting the Cats.
However, it was his sensational defensive performance on All-Australian midfielder Hugh McCluggage that elevated his name into the national spotlight, holding the superstar to a staggering season-low 14 disposals and a single score involvement in Geelong's dominant 38-point victory.
It was the fourth time Mullin had been tasked with tagging a 2025 All-Australian squad member this season - and the fourth time he enjoyed enormous success.
In Round 8, Mullin negated the influence of Brownlow favourite Nick Daicos in a captivating final term, with the superstar recording just three disposals for 17 metres gained as the Pies fell into a three-goal hole that was ultimately insurmountable, despite a late comeback attempt.
The other two masterclasses came against Port Adelaide's 2025 best-and-fairest winner Zak Butters, who was practically invisible when matched up on Mullin this season. The Heather County star held Butters to 20 disposals in Round 10 and then a season-low 10 disposals in Round 21, as Geelong comfortably dispatched the Power each time.
Mullin highlighted his defence-oriented role from his GAA days as a key factor in his success in the thankless job, noting the similarities to Gaelic Football's man-marking schemes.
"It's a funny one. I did play as a defender back home. I was more of an attacking half back, but I did end up getting that sort of man marking role," Mullin said.
"It's slightly more one-on-one back home as well, and that's what I would have grown up with until I got older, where I progressed more into that attacking role rather than defending.
"So, naturally, I had that from being younger. I wouldn't have been overly ball hungry, and I didn't have a forward instinct too much. It was easy to kind of transition back into playing that role for the team as a tagger for a little bit."
Coincidentally or not, Geelong also unleashed fellow Irish utility Mark O'Connor onto Lions goal-threat Cam Rayner in a physical defensive role, a tag which was ultimately successful in frustrating the forward and forcing Lions coach Chris Fagan to adjust his magnets at half-time.
O'Connor has been a key factor in making Mullin feel welcome at the club since he arrived at the end of 2022. He helped persuade the then 22-year-old Mullin to take the opportunity at Geelong, noting that the Cats are "very open" to Irish players going home and competing for their amateur Gaelic clubs in the off-season.
While the tagger label isn't one that Mullin hopes will stick to the pair, the duo's efforts have catapulted Geelong into flag favouritism.
"Mark is more experienced than me, so if he's played on the player before or the individual who I'll be going to, I'll just chat to him about how he found it and different things, like if he has any like cues or advice," Mullin said.
"I'm not sure [taggers] is exactly what we want to be stuck labelled as, but it's definitely something that's helping the team at the minute, so we're both very happy to do that."
Mullin conceded that he's still learning the finer aspects of the game and typically watches other matches as a fan would, but that hasn't stopped him from having an enormous impact on the field as he "keeps things simple".
In fact, three of the five highest Player Rating performances in Mullin's 41-game career have come against top four sides, including last week's qualifying final.
"I guess I don't make it too complicated," Mullin said.
"[I'm told] that I'm going to Hugh [McCluggage] and have a look at their previous games and how they're set up and what positions he might move to.
"Teams will try and move him around a bit to break the tagger, pull apart our system a little bit. It was just getting a little idea of where he might end up, but nothing too overly complicated. Just kind of shut them down."
Mullin says he trusts Geelong's coaches about when he should tag or change his role as he continues to develop his knowledge of AFL strategies.
"I'm still learning the game, really. I feel like my footy knowledge still has a long way to go, so I don't get too caught up in looking at different individuals," Mullin said.
"The coaches know a lot more footy than me, so I kind of wait for them to give me the heads up, to be honest."
Mullin will take to the MCG next week as the Cats look to book a spot in the 2025 AFL Grand Final, and will be hoping to kick another important goal in front of his family, who have flown over from Ireland for Geelong's September campaign.
"[My family] landed last Tuesday, so they flew over one way to wait for the finals series. It's definitely pretty exciting for them, and they really enjoyed it," Mullin said.
"I'm kept pretty busy at the minute, so just trying to balance time and getting downtime in between, but it's been really good."
Geelong are led by several of the game's superstars, including Bailey Smith, Jeremy Cameron and Patrick Dangerfield, but the club's innate ability to find hidden talents has ensured the club's remained a premiership contender year in, year out.
Oisin Mullin is another tale of that success.
His unsung role could see Geelong etch themselves into September folklore once again this season and make him just the fifth Irish player to lift the premiership cup.
