Joanne, who quit the BBC dance show last year after winning with Ore Oduba, believes Shirley is too technical with her feedback and could be more motivational.
She told Radio Times: “In some ways it’s amazing that Strictly’s got [Shirley] because she is so technical. But being so critical – and so technically critical – straight away with everybody, it just puts a little bit of a downer on the whole show.
“If the Head Judge is really technical, the others are sort of following suit a little bit. The judges have gone really technical, and that is a good thing. But they also have to motivate and be a bit more positive.”
The 34-year-old, whose brother Kevin is still on the show, added that Shirley was a “great replacement” for former head judge Len Goodman, but admitted she sometimes missed his positivity.
“I love Shirley,” Joanne continued. “She used to teach me, she is a more than qualified judge and she is a great replacement for Len Goodman – although very different to Len. He did have that bit more positivity about him.
“If Gemma and Aljaž came out last year and did that Quickstep, Len would’ve got everybody in a great mood and gone, ‘What a way to start the show! What a cracker of a number!’ But Shirley is so focussed on technique, which is kind of a good thing. Kind of a good thing…”
Joanne concluded that Shirley “does know her stuff” but thinks she should be more balanced in her approach.
She said: “She probably is one of the most knowledgeable dancers in the ballroom world but it needs to be balanced a little bit with positivity and motivational stuff.
“And I’m not saying you have to undermark or overmark, it’s just the comments – don’t go so technical, also because people don’t understand unless it’s explained on It Takes Two. I thought Len was perfect at that – he gave the balance of knowing his stuff but at the same time it was really positive.”
Joanne isn’t the first ‘Strictly’ star to speak out about Shirley’s technical feedback. Last month her fellow judge Craig Revel Horwood labelled her the “villain” of this series, after she dished out “frighteningly technical” critiques to this year’s celebrity contestants.
Craig said: “Shirley is this year’s villain. She’s frighteningly technical with her criticism, and I know the audience might struggle with that.”
He added: “She was a Halloween baddie in a Cruella de Vil costume – she totally channelled her.”