The Irish singer, who was a mentor on the show, claims that the singer failed to achieve success after her victory on the show because voting public have different taste to music listeners.
"She wasn't on my team so I can't feel that much disappointment," says The Script frontman in an interview with Gigwise. "She won the show, you know, in the final she was 'technically' the best singer. Was she technically the best artist? No. But that's just my opinion.
"She was definitely the best singer on the night, but it was unfortunate, that other people didn't get a look in, ones that would have suited pop music better."
O'Donoghue, who is set to make a comeback with The Script's new Will.i.am-featuring single 'Hall Of Fame' also doubt Mitchell's long-term prospects, suggesting the singer is too dull to perform entertain audiences.
"She's got an amazing voice, but I couldn't see her exciting 80,000 people for an hour and a half, there were people like that on the show, but they got voted off, and it's quite hard."
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