The 28-year-old already looks a different player for the Hammers.
Indeed, the forward was rarely used and, when he was, was played out of position.
It is no coincidence that Sam Allardyce since left the club, with Zarate staying put at Upton Park.
The West Ham owners have made their allegiance very clear and, interestingly, the 28-year-old looks as though he could be repaying their faith already.
Last term, Zarate showed flashes for the Hammers before seriously fading away. When he was loaned to Queens Park Rangers, he made no impact whatsoever and his fitness levels were dire.
Observe him against Lusitanos, however, and you have a different player altogether. The Argentine assisted Diafra Sakho and was a lively, energetic presence.
This was only a Europa League qualifier against an Andorran side, of course, but it showed two things. One: There is a player in there. Two: Zarate has used pre-season to get some sort of fitness back - already a huge step.
Could giving the Argentine a second chance prove a West Ham masterstroke?