How quickly did Firmino "hit the ground running" and is he considered a success yet, undecided or a flop for his price tag?
Same with Lallana? (he picked up his game a lot in the second half of the season and has continued playing well in the Euros).
I think you can only judge a player over the length of his contract. He might start off poorly and then become a good player.. conversely, he might start off on fire, but then turn out to be a flop.
With Mane and with Klopp, I'm optimistic.
This is Jurgen's first big signing and I think it's a good one. He's a very dangerous player waiting to explode. I was very nervous when I heard United were in for him last summer.
I think with consistency, belief and good management, Mane could for us what Mahrez did for Leicester last year. Lallana, Coutinho, Firmino and even Sturridge to an extent (now his pace has diminished a little) are all skillful players like to play "samba football" which buys half a yard of space, but they don't always have the pace to get away from players. Mane, has got good ball skills but he's also got the directness to just kick it past a player and run. Within any team, you need that balance of both. I'm backing him to be a success overall (if not immediately).
