German statistician Andreas Schleicher, an expert researcher in the field of teaching, gave his views on Spain's education model during talks held at the International University of Menendez Pelayo.
"There are too many teachers in relation to the number of students," Scheicher pointed out.
The best educators, Schleicher argues, should be drawn in with better wages and more incentives.
But Carlos López, director of Spain's Educational Workers Union ( FETE), doesn't believe staff reductions will improve standards.
"There have already been lay-offs and those who have kept their jobs are working longer hours as a result," he told The Local.
"PISA's director is right to point out there is a skills deficit and a lack of incentives in place, but I don't believe Spanish schools are unnecessarily overstaffed."
López also admitted there is a lack of motivation among Spanish teachers partly because teaching isn't deemed a professional career, with the social and financial benefits that it brings in other European countries like Finland.
"Teachers in Spain rarely get credit where credit is due," Lopez told The Local.
"Nor do they achieve the salary increases or ease of mobility within the educational system (moving from a primary school teacher post to an admin one, for example) that are more readily available in other countries in Europe."
López also agreed with Schleicher's view that teachers in Spain are "isolated" from other teaching institutions and their methodology.
"We have to work on building a network of schools and give greater support and attention to teachers' needs," López stated.
Not all of Schleicher's views on Spain's education model were negative though, as the German statistician praised the fairness and equality Spain's model offered students of all backgrounds in achieving success.
"The fact that more than half of second generation immigrants say they feel Spanish proves we're an equitable system," López told The Local.