The veteran striker arrived from Udinese this month and is already proving himself fans' favourite.
For the 1-0 win at Rayo Vallecano on Saturday, the Chilean set up Akor Adams for the only goal of the game.
Almeyda reflected: "Alexis is football, he's joy. He doesn't spend the day with his phone in his hand, he talks about plays, players, matches. I'm very grateful he came here.
"He's among the shortest and wins aerial duels. He's not the fastest, yet he beats everyone in terms of pace. He knows when he's under pressure and doesn't lose the ball. That's intelligence."
Almeyda already considers him a leader due to his charisma and attitude: "He arrived with an infectious positive energy. He loves what he does and passes it on to his teammates.
"He's no longer thirty, but mentally he's even stronger."