While he may not have been the quickest of midfielders, Alonso was no slouch and was the metronome to the best side Liverpool has seen since 1990, Real Madrid and Bayern. For Harley to say he would not work in a Klopp side is like saying a legendary classical musician could not make our heavy metal football even better.
Both this and the fast food analogy are perfect, actually. What exactly would a world class chef add to a fast food restaurant? Would they be able to work in that system? Flip a burger quicker? Or would they just want to add their own spin on the Big Mac and get pissed off that they weren't allowed to?
It's like that even with the band. Do you think The Doors would sound better or worse with Jimi Hendrix' solos all over them? Or would he have played to his full potential if having to balance his sound with that of Rayman Zerrick and Jim Morrison?
There's even a real life example of this - Lemmy of Motorhead used to play for Hawkwind. Both he and they were happier and more successful without the other.
As our system stands, with a '1' at the base rather than a '2', Alonso wouldn't work, or would be a bit part player. To not be, we'd need a '2' at the base, and if we had that would it work having Firmino dropping deeper? Or would we need a 'proper' number 9? And if we had that, with Bobby in behind, that could work, but how would that affect Mane and Salah? Would they have to play more like traditional wingers?
Alonso was an amazing player but I'd be astonished if Klopp bought someone like him and played him how he plays Henderson. If he does get Jorginho for that role then, at the very least, I suspect the latter is a lot quicker than Alonso and able to cover a lot more ground - indeed his tackles and interceptions stats would seem to suggest that.