Derec Stockley, head of exams and assessment at the Welsh Joint Education Committee, said the results for the Welsh baccalaureate pilot's intermediate diploma proved young people with relatively low prior attainment did have all-important key skills.
He also revealed that a new pilot Welsh second language GCSE syllabus would be offered.
Results published yesterday show the GCSE pass rate went up 0.4 percentage points to 98.1 in Wales this summer. The percentage of entries resulting in an A*-C grade also rose, by a percentage point, to 62.3 per cent - slightly lower than for the UK as a whole.
However, a report from the Confederation of British Industry claimed school-leavers were scruffy and unable to write or add up. One in three firms reported having to send new employees on basic literacy and numeracy courses. But Mr Stockley said that many school-leavers could probably teach employers "a thing or two" about technology.
Of 722 candidates from 10 colleges and four schools who entered the intermediate bac in 2006, 263 completed within a year and only 167 actually achieved the full diploma.
A further 39 gained the bac "core" certificate. Meanwhile, 211 of the candidates who did not complete the programme this year have deferred until 2007.
The intermediate bac was designed to be a two-year course, comprising four GCSEs (grades A*-C) or vocational equivalents plus a "core" curriculum of key skills; Wales, Europe and the World; world-related education; and an individual investigation.
But most of the candidates were studying one-year vocational courses at college.
Mr Stockley said: "Considering most of these students only had two GCSE passes at A*-C before taking the diploma, the cohort has done remarkably well and demonstrated good key skills.
"The high deferment rate shows it is a tough qualification to cram in over one year and those who pass really have achieved a great deal, with raised self-esteem."
However, Sylvia Davies, spokesperson for fforwm, the FE colleges association, suggested a new foundation level Welsh bac (equivalent to GCSE grades D-F), being piloted from September, would prove more appropriate for these students.
"The completion rate is low. The intermediate level bac is too hard for a lot of these students doing one-year BTEC courses. It's a mismatch," she said.
Only post-16 students have been entered for the bac since it was introduced three years ago. From September, it will be piloted with 14 to 19-year-olds.
Meanwhile, the WJEC is to respond to schools' complaints about its Welsh second language GCSE with a new syllabus.
For the first time, more pupils took the short course than the traditional full course this year - reflecting concerns that the latter is "too demanding" for pupils.
Mr Stockley said: "Taking the short course is not good for the Welsh language. Crash courses are never the best way to learn."