England are struggling to develop a big enough player base to succeed in internationals, says Howard Wilkinson.
Wilkinson was a key part of Premier League academy development
It is unlikely more than 12 Englishmen will play in the Champions League games this week despite England having the most clubs - four - left in the event.
But a study by ex-Football Association technical director Wilkinson showed successful national teams probably need at least 50 players to pick from.
"The job of the England coach will be more difficult," he told BBC Sport.
"Your best players need to be playing against the best players in the Premier League and the Champions League consistently."
During his time as the FA's technical director Wilkinson carried out a study of all the World Cup and European Championship semi-finalists and finalists since the Second World War.
The results suggested that when teams start a two-year qualifying campaign that 50 players are needed in a provisional squad.
The study also revealed that successful teams had players with an average age of 28 or 29 and who had won 30 or more caps.
Consistency, in terms of selection through a tournament, as well as managerial continuity were also important factors to sides succeeding in major tournaments.
"It became apparent from England teams that the pool necessary to sustain a good national team is larger than the 22 when you pick a squad," said Wilkinson, who is chairman of the League Managers Association.
"But it's very difficult to produce 50 world-class performers from a pool of 100.
"That's why Brazil do so well because they have got so many players to choose from."
If the representation of English players is wafer-thin in the Champions League, it is also slowly being salami sliced in the Premier League.
According to a recent Professional Footballers' Association report, the number of English players starting Premier League matches dropped from 363 in the 1992-93 season to 191 last season.
While the representation of English players fell from 71% to 38%, overseas players, who comprised 10% of Premier League players in 1992-93, rose to 51%.
A decade ago, Wilkinson produced the FA's Charter for Quality, which led to the creation of 41 academies in the Premier and Football League and was designed to nurture a recurring crop of young English footballers.
Unsurprisingly, Wilkinson believes there is still much work to be done in the way England organises the production of young players.