Speaking from Sky Sport's studios, the former Milan defender credited Luciano Spalletti's coaching while cautioning that the scoreline needed context.
"The team listened to Spalletti, although I still need to understand the merits of Juventus and the shortcomings of NEC," Costacurta said.
"But there are a lot of players who are becoming important, from Nico GonzĆ”lez to McKennie. And AlajbegoviÄ is becoming good ā we're underrating this lad. In my opinion he'll have a great future."
AlajbegoviÄ, 18, was signed from Red Bull Salzburg over the summer and has been tasked with covering for the injured Kenan Yıldız, who is expected to be sidelined for up to three months. Head coach Spalletti has previously backed the teenager to step up in Yıldız's absence, citing his experience in a similar attacking role and the club's confidence in the investment made to bring him in.
The result offered timely reassurance for Juventus after a mixed start to the season, in which they missed out on Champions League qualification last term and have shown inconsistent form in Serie A so far this campaign, including a painful late defeat to Sassuolo at the weekend.
A comfortable opening night in the Europa League, with a teenage forward among those to catch the eye, will be seen as a welcome building block as Spalletti looks to establish some momentum heading into a demanding run of fixtures.
Juventus have now won four of their last six matches in European competition, a marked improvement on their form across their previous 17 continental fixtures. Spalletti, taking charge of a fifth different club in the Europa League after previous spells with Zenit St Petersburg, Roma, Inter Milan and Napoli, has lost just twice in 18 group-stage matches in the competition across his career, a record that will offer encouragement as Juventus look to make a serious push in this season's tournament.