It is quite funny all that - Wolfgang Frank is the Klopp mentor, end of story. Frank was a Sacchi obsessive, slight extension to story. Rangnik is Klopp's mate, and that's about the size of it.
Good shout Roy - Rafa Hongistein's Klopp book has a great chapter on Frank, his time with Mainz in the mid-late 90s and the influence and impression he left on Kloppo.
Rangnick is an interesting appointment, he's definitely been more 'Director of Football' than coach in recent years, and no one can doubt the superb work he did in the Red Bull group, but I don't think his time at Utd can be anything more than a plaster over a substantial wound - he hasn't the time to extensively drill the players, nor will he likely be afforded a significant budget for signings in January. He is certainly far more tactically aware than Utd's last coach but is known for being divisive - some of the dressing room will go with him, the rest will be dropped. There will be one or two big names with their noses out of joint within the next month.
It's funny that Mancs are heralding him as the inventor of Gegenpressing - which was being utilised by Soviet Teams in a fashion as early as the mid 80s - see Lobanovskyi's Dinamo Kyiv - when he patently is not the inventor, just a proponent and his Schalke and Hoffenheim teams, two of his more recent head coach roles, haven't utilised such a system. We also look at Utd and see a side woefully ill-equipped personnel wise to achieve such a style. We all know from the teething stages that implementing a furious, precise press took nigh on 18 months to two years for Klopp's Liverpool to get right.
He's authoritative, knowledgeable and tactically flexible, all good qualities. Let's see how he handles a calibre of player he's maybe not used to, your Pogbas, Ronaldos and Varanes.