Boycott feels runs are the only way Vaughan can silence the critics
England captain Michael Vaughan has come under increasing pressure after his fourth consecutive failure with the bat in the South Africa Test series.
The 33-year-old has scored 23 runs in four innings against the tourists and one century in his last 22 innings.
With scores of two, zero and 21 in the series so far, Vaughan fell for a first-ball duck as England slumped to 231 all out at Edgbaston.
"Vaughan, I've said for a long time, is not playing well," said Geoff Boycott.
The Yorkshire batsman, who was under intense pressure before hitting 106 against New Zealand at Lord's in May, has also been less than impressive with the bat on the occasions he has played for his county.
"He doesn't play well for Yorkshire - how many times must I tell people? Every player who plays for their country ought to come back to county cricket and be a superstar," Boycott said.
He says he's been working all week with the coach. Well, whatever he's been working at is not working
"If you're that good that you play for your country, you're in the top XI, you should come to county cricket and get millions of runs or wickets."
In his only innings in the first Test at Lord's, Vaughan was bowled by Dale Steyn for two and at his home ground of Headingley the same bowler had him caught at slip before Makhaya Ntini coaxed him into edging behind.
"I'll tell you what's wrong: if you watch his footwork he doesn't get there early enough, he's still coming at the ball when he nicks it and when he misses it," said Boycott.
"There's something wrong - I don't know whether it's his eyesight or what.
"He says he's been working all week with the coach. Well, whatever he's been working at is not working.
"The only way to stop people talking about his form is for him to make runs.
"You wouldn't ask the question, nobody would think the question, nobody would be talking about it if he made more runs and if he looked like he was going to make runs."
Boycott was also critical of Paul Collingwood, who was dropped for the second Test before being recalled for Edgbaston despite having scored just 92 runs in nine first-class innings for both Durham and England this summer.
The all-rounder looked ill at ease throughout his time at the crease and made four runs in 45 minutes before nicking Jacques Kallis to Graeme Smith at slip.
"I can't believe Collingwood was picked," said Boycott. "After leaving him out because he hasn't got many runs, he needed to go back and make some proper runs in county cricket and then come back again.
"He's been a good player, he's shown great character and fortitude, but we've all been there and know how it is when you lose confidence and form.
"His footwork is all over the place, he batted poorly."