Mel was removed from his position at Estadio Benito Villamarin in December following a poor run of form.
However, the club's on-pitch fortunes failed to improve under his successor Juan Carlos Garrido, who was subsequently replaced by Gabriel Humberto Calderon in January.
Despite the managerial merry-go-round, Betis have shown no improvement and - with just five games remaining - a 10-point gap to 17th-placed Real Valladolid means the club look destined to be relegated from La Liga.
And Platas has conceded that the decision to remove Mel - who is now in charge of Premier League outfit West Brom - may have been premature.
"Pepe and the squad had fallen out," Garrido is quoted as saying by Marca.
"But looking back now perhaps we should have given him a bit more time."
