Rafael Benitez was "destroying" Marek Hamsik at Napoli, according to the Serie A outfit's former director Pierpaolo Marino.
Benitez took over as Napoli coach in 2013 after guiding Chelsea to Europa League glory the season before.
The 55-year-old won the Coppa Italia and the Supercoppa Italiana during his time at Naples before leaving to join Real Madrid, where he was sacked seven months into the job.
Under Benitez, Hamsik posted his worst goal tally in the Serie A since joining Napoli from Brescia in 2007, and Marino believes the Spaniard was using Hamsik out of position.
"Hamsik is a good player and Benitez was destroying him," Marino told Il Roma.
"He was being always played out of position and substituted, his potential was being impoverished and consequently the boy was losing motivation.
"Marek simply couldn't react to the situation. Fortunately [Maurizio] Sarri arrived and he now uses him in his ideal role, just as [Edoardo] Reja did.
"We've recovered a world-class player."