She had delivered impressive returns for Adelaide Strikers in the WBBL, for South Australia in the Women's National Cricket League and had made a 97 for Australia A against India, but the national side had just won the T20 World Cup and had also strung together a world-record 18 ODI wins a row.
"I did not think I was in the mix," she told ESPNcricinfo. "It was a bit of a surprise, a pleasant surprise, given the fact I hadn't been around the system for a bit and they'd had so much success but I was absolutely stoked."
McGrath's international debut came against South Africa in 2016 but a back injury then scuppered her chances of being part of the 2017 World Cup. She returned to the side for the 2017-18 Ashes, featuring in the one-day series and the Test match at North Sydney Oval which would prove to be her last outing for Australia with the back issues resurfacing in 2018.
While she had struggled to make much of impression in the ODIs, the Test was a far more successful experience as she scored 47 - adding 103 with Ellyse Perry who would go on to a double century - and claiming three wickets on the drawn match on a flat pitch that would put Australia on the brink of retaining the Ashes.
Memories of that experience have helped McGrath over the last two years as she has brought a new level of consistency to her game having overcome the injury problems to be back among the elite group for Australia.
"That's probably one of the highlights of my career so far, that Test match, the opportunity to pull on the baggy green was really special," she said. "That game against England is something that only comes around every two years so I loved it. The extra challenge of playing the longer format was really exciting. Unfortunately that was the last game to date that I played for Australia so it definitely left me wanting more.
"I remember coming away from the few chances I had just how much I enjoyed it and how it put that hunger in the belly, this is what I want to do. Getting that little taste at the top, when you then aren't in the system, makes you even more hungry to get back there."
There was natural disappointment at drifting down the pecking order, but McGrath focused on channeling her energies into domestic success - which included a maiden stint overseas with Lancashire Thunder in the Kia Super League - and that cumulated in last season's impressive output 327 runs and 14 wickets in the WBBL alongside 261 runs and 13 wickets in the WNCL.
"You have to dominate domestic cricket to be given the chance to play at the top level so after being on the outer for a little bit my thinking switched to just trying to help the Strikers and Scorpions [South Australia] as much as possible and hoping consistency in my own form would eventually get me back to that top level. Whilst it was hard [to lose my place] that motivation to have some state success definitely drove me as well."
McGrath can't put her finger on one thing that has helped change her game, but she cites the role played by a number of coaches. On the batting front Charlotte Edwards, the former England captain who coaches with the Strikers, and Leah Poulton, the former Australia batter who until recently worked at the National Performance Centre in Brisbane, have been key mentors and with the ball Jude Coleman who is part of the coaching staff for the Strikers and South Australia.
McGrath has also been able to watch one of most in-form players in the world, New Zealand's Sophie Devine, go about her work with the Strikers. "It's just the way she [Devine] approaches her cricket and this year she took her batting to another level so whether it was watching from the sidelines or being out there in the middle it was awesome to see and learning as much as I can from here. There were times in the season when I've had questions or been struggling a bit and Soph has been really awesome. She's always there to lend a helping hand."
When awarded her contract, McGrath was talked about as having the potential to cover the all-round role of Perry, should her recovery from hamstring surgery keep her sidelined or a cautious approach is taken ahead of the World Cup, while her leadership qualities have also been noted with the captaincy of Australia A.
"It's a pretty cool comparison," McGrath said. "I don't think anyone can quite replace Pez, but I think I have capabilities as an allrounder and I want to learn as much as I can off her and the way she approaches her game.
"I feel like I've got my game to where I am a genuine allrounder. I feel as though whether I'm a batting or a bowler depends on what team I'm in. For South Australia I'm probably a bit more of a batting allrounder but opportunities in the Australia side are probably as more of a bowling allrounder.
"[Captaincy] is a side of my game that's still relatively new to me but it's a side that I absolutely love, it helps my own game and I definitely thrive on it. I'm a pretty laid-back person, pretty cool and calm, but someone who leads from the front with my actions and need to get better at the communication side of things. At the moment I'm a little bit the quiet achiever that is trying to be a bit more outspoken, a bit more encouraging. Every game I do captain I learn so much from."
As McGrath hopes for a return to Australia colours in September when New Zealand are due to tour, the World Cup across the Tasman early next year is the massive prize on the horizon despite the uncertainty caused by Covid-19. "That is definitely the big carrot and it's hard not to have aspirations to be playing in it. The World Cup is the ultimate event and for me I probably see myself as more of a 50-over player so I've definitely got might sights set on that."