The Toffees beat off competition from a host of clubs, including Atletico Madrid, who were no doubt hindered by their registration ban, to sign Sandro for a rather paltry €6m (£5.2m) from Malaga in the summer.
Despite much fanfare, the 22-year-old failed to make any sort of impression under Ronald Koeman and interim boss David Unsworth and he wasn't included in new manager Sam Allardyce's match-day squad for the win over Huddersfield Town on Saturday (2 December).
Dominic Calvert-Lewin and Oumar Niasse are both ahead of Sandro in the pecking order at Goodison Park, and with Everton likely to sign a new striker in the January transfer window, the Spaniard may have to seek pastures new in the coming weeks.
Everton boss Allardyce recently said that the likes of Sandro and Davy Klaassen will get chances to impress during the gruelling festive period, but the former reportedly has designs on a return to his homeland, with Valencia said to be interested in a loan deal in January.
Los Che do not have many forward options available to them, with Simone Zaza and Rodrigo the only recognised strikers available to Marcelino at present. Sandro would be a reasonably cheap and assumingly effective way of bolstering Valencia's forward line, and Marcelino did little to dampen the flames surrounding a potential move for the Spain youth star.
"He is a good Spanish footballer and knows the league," Marcelino told Radio Marca. "I am not going to talk about any player who is not here.
It remains to be seen if Everton decide to part with Sandro or afford another chance to prove his worth under Allardyce, who confirmed that signing a new striker in the January transfer window was a priority for the resurgent Merseysiders.
Valencia coach Marcelino may be able to get his hands on Everton's forgotten man next month, but he is also keen to keep one of his current loanees at the Mestalla Stadium on a permanent basis. Goncalo Guedes has been one of the major driving forces behind Valencia's sublime start to the new season, and Marcelino is already hopeful of prising the Portuguese attacker away from Paris Saint-Germain on a permanent basis.
"We speak of the majority, not to mention the totality of the players on the squad, from the sporting and human point of view, he fits perfectly into what our game idea is, he has quality and a great future ahead of him," Marcelino said.
"I would be happy to keep Guedes for this season and the next, but it is Valencia who must decide if we can do it directly."