"One memory, a shock to the system - and I won't name names - concerned a girl who had just lost in a tournament," she says.
"Her dad, let's just call him a bit nuts, was making her do sprints along the corridor at the hotel until she couldn't walk any more.
"That's when I thought, 'Oh my God, what have I got myself into?'
"And that's just one story ... there were more like that. Lose matches and there would be punishments, whether by over-training them, or verbal abuse. It was some coaches, but mainly parents.
"It was very tough to see and you really felt for those girls. It gave me a sense of fear and sadness at the same time."
But the Erakovic family story is very different to that, and pivotal to her having a life in tennis.
Her parents, mother Liliana, an Auckland University associate professor in business management, and father Mladen, a ship's captain delivering oil around New Zealand ports, came here to escape the horrors of the break-up of Yugoslavia.
The family hailed from Split, in Croatia, and the situation was complicated by her parents' mixed ethnicity marriage, her mother being Serbian, and her father coming from Montenegro and with Croatian heritage.
"If you asked any family who came to New Zealand from that area 20 or 30 years ago, it would be the same story," she says. "Maybe they were Croats in Serbia, or Serbs in Croatia, or maybe they were Serbs and Croats in Bosnia. There was no unity ... a lot of hate."
Marina was six and sister Julia nine when they arrived, and they spoke no English. The family crowded into the home of friends in Mt Roskill for the first six months, Liliana and Mladen sleeping on couches.
Her father was a passionate recreational tennis player in Split, at the famous club which produced Goran Ivanišević. Julia and Marina picked up their first racquets there, little Marina confined to hitting balls against a wall.
Marina thinks that carrying on with tennis in Auckland was a way the family could hold on to some normality, having left their homeland, arriving with very little, as two well-educated parents began doggedly rebuilding their lives and making better ones for their children.
As Erakovic calls it, she was an extremely introverted kid, the youngest and quietest in a talkative family. Tennis was a sanctuary.
It soon became more than that. She rose to fifth in the world as a junior and on seeing star peers such as Victória Azárenka and Caroline Wozniaki making their mark, Erakovic always had her sights on turning pro on leaving school.
Guided by Chris Lewis, one of New Zealand's finest, she at least had some sort of insight into what life on the professional road would be like, and her father travelled with her on his regular weeks off.
Memories good and bad come easily to Erakovic, who had career earnings of $3.8 million.
She rose to a rank of 39 as a singles player, winning one WTA title in Memphis. Her best moments include a win over then world No4 Azarenka, and notable opponents include the great Serena Williams.
"The thing that surprised me was her game was great, but it didn't blow me away," she recalls of Williams.
"She had been an idol of sorts and you build it up in your head - how would I fare against this person? But on the court, it's just tennis. I do remember thinking she serves amazingly well."
In fact, far lower profile opponents provided days when Erakovic felt she was up against unstoppable forces - namely Virginie Razzano of France and Australian Casey Dellacqua.
She also remembers practice sessions against a young Madison Keys from the United States, and Garbine Muguruza of Spain, when she felt potential greatness was on the other side of the net.
"I just remember the intensity of Muguruza - every ball you hit came back faster than you hit it there. You had no time - that's when you know they've got something."
Although Erakovic never pursued doubles as her primary focus, she had the greatest success there, winning eight titles and rising to a 25th ranking.
Some partners were special, such as Thailand's Tamarine Tanasugarn who, she recalls humorously, had become confused about the score and didn't realise they had won their 2011 Wimbledon quarter-final when the final ball had been hit.
"She is the loveliest person, and we had so much fun on and off the court," Erakovic says.
"We'd go to movies, she'd take me to great spicy restaurants, we're still in touch ... Elena Vesnina was another, where we had a lot of fun on the court."
As for some other partners ...
"There have been a few dramas ... once you start losing, a different personality comes out. Let's just put it that way. You are a little stunned by it but those partnerships don't last.
"One of my partners got so frustrated, she didn't care any more. She didn't want to play. It's tough, you are trying to motivate them, be a coach out there.
"I always looked for partners I got along with, as opposed to someone who was just playing well."
Erakovic also felt honoured to be elected to the WTA by her fellow professionals, doing a four-year stint in which she tried to get a better distribution of prize money, on finding that players outside the top 70 struggled to break even.
As has been reported over the years, Erakovic - raised on her father's love of Fleetwood Mac and the Motown sounds - become a keen guitarist and apparently has something of a musical knack. The one-time classroom pencil tapper is now a budding drummer.
Along the way, she was able to indulge her passionate love of music on the tennis tour and has 42 ticket stubs to prove it, from her favourite concerts (Muse, The Killers, Beyonce, Lionel Richie, Adele) to a "shocker" involving a "prima donna" Mariah Carey.
Essential reading has included Quiet: The Power of Introverts in a World That Can't Stop Talking.
With the next stage of her life at hand, Erakovic says she will never forget the sacrifices her family made for her career, and these include Julia barely seeing her father for years because he was on the road supporting Marina.
While music and finishing her economics degree call, and she is enjoying everyday things such as vacuuming, experiencing winter and just living in Auckland again, tennis holds an uncertain part in her future.
Merely picking up a racquet brings reminders of the many injury problems, particularly the final back issue which made her legs go numb and badly affected her hamstrings. She also fears picking up a racquet with diminished skills.
She even declined to join her family on a Croatian holiday this year, during an injury-forced hiatus, unable to face yet another plane trip.
Through all the ups and downs, there was a particularly glorious day.
While Erakovic was unsure of the actual score, the record shows she was 0-4 down against world No12 Sara Erani from Italy in Tokyo four years ago when the magic arrived.
"I could do no wrong in that game. Every ball l hit felt like the sweetest thing in the world," said Erakovic, who tore Erani apart with 39 winners.
"When it first happens, you go, 'Yeah, how can I do this all the time?'
"Then you realise it is something you will only experience sometimes, bless its little heart. So enjoy it, because most of the time, it is a battle.
"Life on the road isn't for everyone - you have to be a specific type of person, independent, able to pick yourself up.
"It can get very lonely, it's not all glamorous, a life of going back to a hotel room, trying to find the right food, sleep well, dealing with thousands of things which come your way.
"There were probably a lot more lows than highs but the highs were amazing.
"When I had to write my retirement press release, I started looking back and realised I did really well. I should pat myself on the back. I did the best I could, I've given everything. Wow, good job Marina."
