Four straight defeats under the Chilean saw West Ham labelled 'pathetic, clueless and lazy' and Pellegrini unsuitable.
Fast forward two weeks and the Hammers have turned things around dramatically.
A 3-1 victory at Everton was followed by a 0-0 draw against Chelsea the East Londoners were unlucky not to win.
A hugely impressive 8-0 win over Macclesfield in the Carabao Cup on Wednesday night showed just how much confidence has been boosted at West Ham.
It was also further proof the players are starting to really buy into Pellegrini's famous attacking style.
After being tipped as relegation candidates after their poor start, Eden Hazard and his Chelsea boss Mauricio Sarri offered a more considered view on West Ham after the 0-0 draw with Chelsea last time out in the Premier League.
The Belgian superstar's comments showed what those in the game really think of Pellegrini's West Ham.
"Last season we lost here 1-0, we know it's a difficult place to come and win games," Hazard told Sky Sports.
"We could win because we missed chances but we also could lose because they miss a lot of chances so I think we are not "happy" with the draw because we always want to win but when you see the chances they have I think we can be happy today.
"At the end the draw I think is fair, both teams are happy."
Meanwhile Sarri said pre-match West Ham would be his side's most difficult game of the season and admitted he could not believe how they had struggled under Pellegrini.
"We knew that West Ham are a very good team that it was a very difficult match," Sarri told Sky Sports.
"They are really a very good team and now after they have won away against Everton they have confidence and I knew it was a very difficult match."
This from the manager and star player of a side that started the season with five straight wins and put Liverpool to the sword at Anfield in midweek.
It is quite the compliment and shows how those in the game really see Pellegrini's Hammers.
West Ham fans will just be hoping they can continue going from strength to strength and build something special under their new boss.
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