The 20-year-old penned a short-term deal with the Aviva Premiership champions on Tuesday.
Matera has been brought in as injury cover for Tom Croft, who will miss the rest of the campaign with knee ligament damage.
"He's one of the best young players in the world," The Guardian quotes Cockerill as saying.
"He's got all the raw ability and if you don't get him now and he goes to France first you'll never see him again.
"You have to take the punt on the guy that might be with you for the next 10 years."
Leicester begin their Heineken Cup campaign on Friday night when they travel to Ulster.