There's been a lot of talk about that controversial move by Sporting. Even though Marco Silva continued to show promising steps (after great seasons leading Estoril) at Sporting, soon after the year started he and the president started having problems, so it was a matter of time he was sacked. Since he started getting better results ending with the win at Portuguese Cup final, it would seem very hard to sack as the fans respected him very much.
Bruno de Carvalho, Sporting's president, makes a bold move and signs Jorge Jesus (who won 2 leagues, 2 league cups, 1 national cup, 1 national supercup, besides reaching Europa League final in the last couple of seasons at Benfica). His contract expired and Benfica's president wanted a change (even more when found out Jorge Jesus was negotiating with Sporting)...
So, Sporting signed Jorge Jesus even before sacking Marco Silva. Most of the fans didn't like this, as Sporting decided to do it unilaterally (not having to pay the remaining of his contract) based on stupid things like him not using the official suit on a cup match, and stuff like that...
Marco Silva always had a nice posture, and it's still regarded as a very promising and serious manager. If you're curious because Olympiakos link to him, he's talented, and wasn't sacked because of his abilities (as Benfica and Porto had better teams and he won the cup... the first Sporting trophy in the last 8 years).
Benfica was rumoured to sign him but our president prefered Rui Vitoria who is claimed to work well with youngsters (Benfica made a great investment on our youth department but Jesus didn't like to use young national players very much). The idea is to start taking advantage of players like Andre Gomes, Bernardo Silva, Cancelo instead of selling them...