Well, in Portugal he took over a team that was midtable in the second tier. In his debut season as a manager, he lost 4 out of 24 of his next games as he took them to promotion as champions, winning Manager of the Year in the process. He then took the side to their second highest ever finish of 5th with a first time European qualification in their history, before leaving them after finishing 4th the next season.
He then joined Lisbon where he ended a six year trophy drought by winning the cup, and was eventually only sacked by Lisbon's mad chairman because they wanted to bring in Jorge Jesus. A bit like if we sacked Martinez because we thought Mourinho would come to us, to give you an example for us from a while back.
He then went to Greece with Olympiakos, where he broke the record of 11 consecutive league wins (from the first day of the season!!) and beat Arsenal 3-2 in Europe. They then set a European record of straight wins in the 21st century, before he eventually left citing personal reasons.
He then went to Hull who had started the season with 8 registered first team players and nearly kept them up if not for an implosion on the final two games of the season (should be noted though that he beat the Kopites and United in that time with Oumar Niasse up top)
Then finally he had Watford flying until we went and turned his head
I don't see at all how you can look at anything from his previous record and assume he needs world class players to play his style of football