Rio Ave assistant: Celtic have made great signing in Balde
Balde has joined the Hoops for £1.8million which leads Cathro to believe that the Scottish champions have lured a quality player to Glasgow for a reasonable price.
"It's a great signing for Celtic - a lot of credit should go to the person who put his name on Neil Lennon's desk," he told SunSport.
"Based on today's market, he's possibly too good for the SPL.
"The price they've paid leaves a lot of margin for making a tidy profit when they sell him on to a higher level, as I believe they will. It's good business."
He added: "Balde attracted attention. Guimaraes have been consistently good throughout the season and he's been a big part of that.
"He's a good all-rounder. If Celtic are looking for a target-man then I can understand their interest because his 'simple' game is very strong.
"He's aggressive, uses his body intelligently and is a threat at set-pieces but there's a lot more to him than that.
"He's quick on the ball, protects it well and takes up dangerous positions for counter attacks.
"He's a long way from just being a big lump. The guy can play.
"Scoring goals in the Portuguese top flight is a lot more difficult than in the SPL."