Robin Roefs turned heads last season, as did Noah Sadiki and Brian Brobbey will no doubt be in the thinking of more clubs after carrying his form from club to country at the ongoing World Cup.
But losing Granit Xhaka this summer wasn't something that has been in anyone's thinking on Wearside.
Indeed, Xhaka himself said he's "not even thinking about a transfer" in an interview with Blick earlier this month.
But now, Xhaka has now reportedly expressed a desire to join Chelsea after his former Bayer Leverkusen boss Xabi Alonso prioritised a reunion with the midfielder at Stamford Bridge this summer. The shock interest from Chelsea emerged on Saturday.
Here's everything we know so far:
CHELSEA'S INTEREST AND XHAKA CLAIMS
Alonso has identified the need for experience and leadership in the Chelsea ranks and believes Xhaka - who was the beating heart of his Leverkusen team - is the ideal recruit.
Chelsea's strong interest emerged on Saturday, with a host of high profile and well-sourced transfer reporters in Europe claiming Xhaka wants the move. Fabrizio Romano claimed on Sunday morning that Xhaka is "driving the move personally".
That sort of talk clearly isn't plucked from thin air.
It's also claimed that personal terms have been agreed, with Chelsea said to have been in contact with Xhaka's representatives.
But as of Saturday night, there'd been no contact between the clubs and reports also emerged from well-placed sources in the capital claiming Chelsea wouldn't be willing to pay the sort of fee that has been circulating on social media, which is between £25m and £30m. That is significant.
SUNDERLAND'S STANCE
That's because Sunderland are in a strong financial position where they're under no pressure to sell.
Xhaka still has two years to run on the three-year deal he signed when he joined the club last summer.
The Northern Echo understands Sunderland's stance is strong and clear: offers would not be welcomed and they consider their captain not for sale.
That's understandable and admirable but we also know how football works and if, as is reportedly the case, Xhaka wants the move, it would be hard to stand in the captain's way.
Florent Ghisolfi himself admitted earlier this year that Sunderland's model falls down if the Black Cats stand in the way of lucrative moves for players. But that doesn't mean the Black Cats roll over any time there's interest in a star.
Sunderland have shown on countless occasions in recent seasons that they can recover from high profile sales, and while Xhaka is the most extreme example, given all that he offers on and off the pitch, no player is bigger than the club.
In terms of what Xhaka is worth, well it's so difficult to nail down a figure given the midfielder is 33. There's no sell-on potential for buying clubs.
But Xhaka is undoubtedly worth more than he was when Sunderland signed him from Leverkusen a year ago. Yes, he's a year older, but he's demonstrated that he's still among the very best in the Premier League, and, as alluded to above, there's all that he offers off the pitch. Xhaka might be turning 34 the month after the campaign starts, but there's a reason Alonso and Chelsea want him.
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WHAT'S XHAKA SAID?
Nothing since the weekend transfer talk emerged. The midfielder is away at the World Cup captaining Switzerland and preparing for a last 32 clash with Algeria in the early hours of Friday morning.
It's not clear whether Xhaka will speak to the media ahead of Friday's game, but when Switzerland head coach Murat Yakin holds his pre-match press conference he will almost certainly be quizzed on the matter given who it is we're talking about here.
But quotes from a Xhaka interview with Blick earlier this month now feel particularly relevant.
Xhaka told of how happy and settled he feels in the North East and said he welcomed a summer without any speculation surrounding his future.
“It’s a bit like home for me," he said of Sunderland.
"The city feels like Basel. Like the St. Johann district where I grew up. You can only perform at your best when you feel comfortable in a place.
“For me, the most important thing is that my family is happy. And we are in Sunderland. I’m not even thinking about a transfer. I’m really happy to finally have a summer without any speculation about my future. That’s rarely been the case in recent years. This allows me to fully focus on the World Cup.”
He also reflected on Sunderland's success in his first season at the Stadium of Light.
“To be honest, I’m not surprised.
“Throughout my career, I’ve always made all my decisions based on my gut feeling. The move from [Bayer] Leverkusen to Sunderland wasn’t a snap decision. I had a lot of discussions with the owner, sporting director, and manager before I signed.
“Sure, you could say that winning the league title with Leverkusen was a bit of a surprise. The same goes for this season, finishing seventh in the Premier League as a newly promoted team. But I see it a little differently because I see all the hard work that goes into these successes. If you work hard day in and day out, you can achieve a lot.”
WHAT'S FLORENT GHISOLFI SAID?
When Ghisolfi was quizzed about potential exits earlier this month, Sunderland's director of football said: “Personally, I am never afraid to sell a player. Sometimes, we need to refresh the team, and I am sure and confident that we can replace them. It is a different situation than in my past because we are competing in the Premier League, so along with that, experience is important.
“Last summer, people could say we brought in players with a lack of Premier League experience, and that is true, but it was difficult to buy players with that level of experience. This summer, we should be attentive to trying to keep this level of Premier League experience we have now, keeping this team together. We want to keep every starter. We want to keep the team together, but if we have to sell someone then you know how the football industry works, it will be okay. It will be okay for us, we will replace him.”
Xhaka was a transformational signing last summer. His arrival paved the way for more top class recruits, for targets suddenly looked at Sunderland differently after someone of Xhaka's profile and quality had committed to the Black Cats.
Earlier this month, Ghisolfi was asked whether Xhaka will be used in this summer's transfer efforts. Would he ever, for example, be asked to speak to potential targets to sell the Sunderland project and vision?
"Sometimes it's natural because we have a huge connection," said the director of football.
"We have the same view, the alignment from me, the ownership to Granit the captain.
"But I tried during the season not to put everything on his shoulders because it's also important he's focused on the pitch, the team and fresh in his mind.
"We try to find a balance. He felt the project (last year), Kyril spoke to him, I spoke to him and he spoke to the manager. He felt the project, he felt the people - so it works all together."
WHAT HAPPENS NEXT?
When a player wants a move, they so often get their wish. It's the way modern football works.
Xhaka clearly wasn't anticipating this to happen this summer and the midfielder can be taken at his word for what he said and when he said it. But the fact it's Alonso - with the pair enjoying such success in Germany - who wants him makes it feel like something of a gamechanger from the midfielder's perspective.
This is not a story of a player who would have jumped at any given opportunity. Everything that's been said about Xhaka - and his displays on the pitch - point to total commitment last season.
But if that commitment is at all in question - and again, we're just going on what's been reported here - can he have the same impact in the dressing room moving forward? And what impact would it have on the dressing room if Sunderland stand in the way of a move a key player wants?
But none of that matters unless Chelsea pay what Sunderland deem Xhaka to be worth. The Black Cats won't want a protracted saga but Xhaka still has two years left to run on his contract. The Black Cats are in a strong position.
"This is just the beginning," said the midfielder on the Stadium of Light pitch after the final day victory over the Blues secured Europa League qualification for Sunderland.
Nobody at that stage would have predicted this scenario just a month down the line.