COMMENT: So will he do it for Chelsea? Jurgen Klopp and his principles. Will he change them? He didn't do it for Pierre-Emerick Aubameyang. Nor Henrikh Mhkitaryan. And he won't do so for Robert Lewandowski...
...but could Christian Pulisic be the exception? Could the American lad, who at 20 just captained his country for the first time, be the one jewel from Borussia Dortmund whom Klopp chooses to take to Liverpool?
Well, thanks to Chelsea, we'll know all this time next month. With the threat of a transfer ban hanging over their head, the Blues have already made their move. Rather than roll the dice on UEFA finding in their favour over claims of Financial Fair Play violations, Chelsea ain't hanging around. If they're going to be barred from working the transfer window next summer, best to stock up now.
Coming from Germany, a first bid was lodged last week - and immediately rejected. Dortmund are prepared to sell, but Chelsea's offer fell well, well short of their €80m valuation. A meeting last month with Pulisic appears a smokescreen. A mechanism to cool the jets of Pulisic's father and agent, Mark, and those intermediaries close to the family. But with his contract up in just over 18 months - and with the player refusing to sit down and discuss new terms - BVB will sell in January, but only on their terms. With the exciting emergence of Jadon Sancho and Jacob Bruun Larsen, Pulisic is now viewed as expendable by the BVB board.
Reacting to Sunday's story, Michael Zorc, Dortmund's sports director, offered an unconvincing response: "We've known about these rumours for many years. We're still planning with him for at least until the end of this season."
But Chelsea will come again. With doubts surrounding Eden Hazard's commitment. And the likes of Pedro and Willian now the wrong side of 30. Maurizio Sarri and those above him recognise the need for rejuvenation. And given the UEFA threat, the need to get it done quickly.
But where does that leave Klopp? Given his BVB roots. His ever ready willingness to talk up Pulisic publicly. And the American's reflected admiration. It would appear a no-brainer. An easy fit. For Liverpool, Pulisic can be the 2019 version of Nabil Fekir. Only this time the deal gets over the line.
Or does it? After all, not a month ago, it was the Liverpool manager who declared all those stories of reunions with past players were wide of the mark. Mario Gotze, like Pulisic, another of his old proteges being mentioned as a Klopp target earlier this season.
“We didn't look for players we had already worked with," the German remarked in response. "If you do that, you know their good, their bad and you wonder whether you will do it again.
“It's not boring but you know everything about each other so how can you develop? Where is the next step? Where is the next push for development?"
So that's it, then. Pulisic is Chelsea's to have - so long as they come up with the readies. Sarri will have his new No10. Gary Twelvetree and his marketing team the biggest talent ever produced by US soccer. For Sarri, he's a younger, more powerful version of Dries Mertens. For Chelsea, he's the one we've all been waiting for since Freddy Adu. So, case closed...
Not so fast...
Y'see Klopp did leave some wriggle room when dismissing the theory of transfer reunions. And it all centred around what Pulisic has in abundance - potential. Indeed, if we're really to parse things, the pair of 'em barely spoke when Klopp was in charge at the Westfalenstadion.
"When I came to the club, he was already there as coach," recalled Pulisic. "I did not really get to know him personally, but I've heard many stories from my fellow players who played for him - and loved it."
So they're basically strangers. A player for Klopp to truly get to know. A project there - ready and waiting. Is Klopp really going to stand by and let Chelsea ferry away Pulisic unopposed? Indeed, are Liverpool's Boston owners? No chance.
After all, Klopp's comments on such matters can always be taken with a pinch of salt. Just think of the case of Paul Pogba, 100m quid and, erm, Virgil van Dijk's fee...