Getting Mané for £36m and Robertson for £8m was also extremely good business, whether it was obvious or not. There is no guarantee that these types of players take the step up from mid/bottom PL teams to title challenging teams. Same with Mac Allister even though it's early.
It's not praise of Klopp for picking them, to be clear. It's just during this time period, they've made some really shrewd moves from the PL. Maybe my baseline is just in the dumps, because I'm comparing it to our moves to get Maguire, AWB and the like. But you can also look at Chelsea - their Cucurella and Caicedo moves look extremely dodgy, even though at least Caicedo was also considered one of the best in his position, when he was at Brighton.