Marshall: England Shields' move 'desperate'
Jones included New Zealander Shields in his 34-man squad for the three-Test tour of South Africa next month even though the Wasps-bound flank has never played in England.
The 27-year-old, who opted for England after failing to make the All Blacks, needed a special dispensation from New Zealand Rugby to join Jones' squad.
Former All Black scrumhalf Marshall said Shields' selection raised doubts about the depth of talent in English rugby.
"They were trucking along nicely and really struggling with their selections because they had a good group of talent and weren't sure who to play," he told Radio Sport.
"But now they're seeking outside players. How all of a sudden has that talent dissipated to the point that they're now having to look for better options?"
Jones is attempting to get his side back to winning ways after a disastrous defence of their Six Nations crown which saw them lose three successive matches.
Marshall said that five months ago England looked like New Zealand's main threat at the 2019 Rugby World Cup, but Ireland had now taken that mantle.
He said the momentum that England built under Jones had faltered and the coach was looking to reignite his team.
"What this whole Brad Shields saga indicates to me is that all of a sudden they've become a little more desperate than they looked," he said.
"They're nowhere near as rhythmic as they were and I think they're a lot more vulnerable."
England will play their first Test against the Springboks at Ellis Park on June 9.