The 23-year-old missed out on selection for the original Lions squad but received a pre-tour call up after Munster's Alan Quinlan was ruled out prior to departure.
And having returned home with his reputation further enhanced, Cockerill is confident Croft can establish himself as one of the best back-row forwards in the world.
"He was enormous for the Lions," Cockerill told the Leicester Mercury.
"When they picked him they found out he was really good. And he will get better, more robust, more physical. I think he will be a world-class player."
Cockerill, who won 27 caps for England as a hooker and played alongside plenty of Lions and England legends, believes the former Oakham schoolboy has what it takes to establish himself as one of his country's true greats.
"If he keeps working on his game he will be as good as anyone we have seen - Hill, Dallaglio, Back, Teague, Winterbottom," added Cockerill, from his club's training base in southern France.
"From an England point of view, Croft has had a very good season and proved on the Lions tour what a valuable asset he is.
"He provides something a bit different. England need to utilise his strengths above and beyond other players."