There will be no English representatives in the quarter-finals of the UEFA Champions League or Europa League this term, leading some pundits to suggest the Premier League is in decline.
And Moyes, now in charge of La Liga side Real Sociedad, believes the quality of the English top flight has deteriorated.
"Maybe we have talked up the Premier League more than we should," Moyes, who took over United as champions and left them seventh in the table, told 5Live.
The Scot, who spent 11 years as manager of Everton, also feels that Spanish teams have proved that vast sums of money do not need to be spent to enjoy success on the continent.
"Of course, the top clubs in Spain spend a lot, but the other teams can't," he added.
"Atletico [Madrid] have had financial difficulties over the years, but they have still reached finals. Valencia, Villarreal, they have have got quite far in the Europa League.
"So maybe we do go over the top about our [Premier] league. This year it is probably the poorest Premier League I've seen in a long time."
