The Argentine striker joined Queens Park Rangers on loan from West Ham in the first week of January for until the end of the season.
However, with the Hammers looking for a striker late in the January transfer window, it has now been revealed that the 27-year-old could have returned to the Boleyn Ground.
"A lot of moves were blocked for various different reasons so I'm not that bothered,” Allardyce told West Ham’s official website when asked about Emmanuel Adebayor’s blocked move from Tottenham Hotspur on deadline day.
“From our point of view it left us a bit frustrated, and especially Carlton Cole on the basis that he would've moved had Adebayor joined, as it happened we couldn't afford to let him go.
“At one stage we even thought Mauro Zarate was going to come back, but that didn't happen either. It was a frustrating day, originally it didn't look like we were going to be active until the very end, but then we picked up five injuries and now we are very short.”
West Ham have been struggling with injuries lately, with James Collins, Winston Reid, Guy Demel, Diego Poyet, Doneil Henry and Andy Carroll all doubtful for Sunday’s Premier League clash against Manchester United.
But it is still quite surprising to note that the Hammers were willing to take back Zarate, despite the fact that the Argentine has not been at his best since his return to English football.
The former Lazio star joined West Ham in the summer of 2014 amid much fanfare, but he struggled to make a huge impact in the first half of the season, although he was not given too many chances.
Zarate scored two goals and created seven chances in seven Premier League appearances for the London outfit, while having a laudable pass accuracy of 84% and a fantastic shot accuracy of 100%.
The fact that West Ham were willing to sign a striker they thought could not do the job for them shows just how dire they were to get in someone on transfer deadline day.