The Irish pundit was unhappy with the Tottenham Hotspur duo.
The Spurs pair were part of the England team which lost 2-1 to minnows Iceland and exited Euro 2016 at the last-16 stage on Monday night.
Both men had fantastic seasons at club level last term but they, along with a host of high-profile England stars, struggled to impress in France this summer.
Dier scored a wonderful free kick in their opener versus Russia, but on the whole he and Alli looked quite a bit away from their respective Tottenham form.
And Irish pundit Dunphy put the boot in even more after the game last night.
"Dier, Dele Alli, they're not real players," Dunphy said on RTE Sport. "The players just aren't there anymore [for England]."
Tottenham had five representatives in the England squad but none of them covered themselves in glory last night.
Harry Kane endured a torrid 90 minutes, whether it was cheaply losing possession or mis-hitting free kicks, while right-back Kyle Walker was perhaps at fault for Iceland's equaliser - 83 seconds after Wayne Rooney had opened the scoring.
Danny Rose was perhaps the lesser of the evils but, with the exception of maybe Marcus Rashford, who had just four minutes to impress, it was a shambles collectively last night.