The west London side confirmed on Friday night that they had secured a deal to sign the Brazilian forward on a temporary basis until the end of the current campaign.
Pato, 26, had been heavily linked with a move to the Premier League and was touted as a possible target for Liverpool in the build-up to the January transfer window.
However, now the former AC Milan star has signed for the champions, former Tottenham and Queens Park Rangers boss Redknapp has admitted his surprise at the transfer deal.
Writing in his column for the London Evening Standard, Redknapp said: “If I was a Chelsea fan, I wouldn’t be getting too excited about signing Alexandre Pato.
“They have already got Willian, Oscar and Eden Hazard — where is Pato going to play? They have about four or five players just like him so I don’t see where he fits into Chelsea’s team.”
He continued: “I was offered Pato at QPR this time last year but we turned him down because he wasn’t what we needed at the time. He played against my Tottenham team when we faced AC Milan in the Champions League but seems to have faded away and ended up back in Brazil. He’s a little bit like Bojan at Stoke.
“He started off with a huge reputation as a kid but never really fulfilled his potential. Bojan did really well at Stoke but now he looks like he’s lost his form.
“Signing him looks like Chelsea just getting another body in, really. He’s got the ability to play anywhere but he’s not in the same class as Hazard.
“OK, if they get injuries, then it is different but who drops out to accommodate him if everyone is available?”
Pato could be in line to make his Chelsea debut when the Blues travel to MK Dons in the fourth round of the FA Cup on Sunday afternoon. The Blues beat Arsenal 1-0 in the Premier League last weekend.
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