Former England hooker Phil Greening says the team's World Cup chances would have been boosted if players like Dave Strettle had been called up earlier.
Greening (centre) coached Tait and Strettle in England's Sevens team
Coach Brian Ashton gave the winger his first cap in this year's Six Nations - Greening says former boss Andy Robinson was too cautious in his selections.
"The people he's brought in should have been there a year ago - Andy Robinson should've done it," he told BBC Sport.
"Then they'd have 10 or 12 caps and we'd have a more experienced side."
Greening has worked closely with Harlequins winger Strettle and Newcastle centre Tait in his role as assistant coach to the England Sevens side, and both have become regulars for the full side this season.
I really do have a lot of confidence and expect England to at least get to the semi-finals
Speaking at the London launch of his Sporting Chance Foundation children's charity, Greening said he was full of confidence about England's chances in France, but blooding the likes of Strettle and Tait earlier would have helped even further.
Ashton's preliminary squad of 46 has been cut down to 40, with a further cut expected before the final party of 30 is named on 14 August.
And Greening said the resulting rise in tension in the squad as players fight for places is a sign of healthy competition.
"What you need in the squad is to know that if someone's not on form, then there's someone ready to take his place," he said.
"Pressure breeds competitiveness, which breeds success. At Wasps, we used to say you only borrowed the shirt for one week, you had to re-earn it the next. If you have that attitude in the squad, it breeds winners."
Strettle made his England debut this season against Ireland
Since Ashton replaced Robinson as England's head coach, the team have produced an erratic Six Nations campaign and been hammered by South Africa.
They have three more warm-up games in August before their World Cup campaign opens against the USA in Lens on 8 September.
But despite wobbles along the way to starting the defence of the trophy, Greening said he was optimistic about England's chances.
"I really do have a lot of confidence and expect us to at least get to the semi-finals, and if you get that far, you're in with a shout," he said.
"If Brian gets the team to play as they can, with the talent they've got available, they could really turn some heads."
But despite his good feelings about England, he said it was hard to look beyond favourites New Zealand.
"Australia didn't do anyone any favours when they beat the Kiwis the other week," he said.
"If they'd won that, it would have been the same old story, the All Blacks coming into the World Cup full of confidence but choking.
"I'd love England to be there, but after that stumble, I can't see New Zealand not coming back and winning it."