The 27-year-old, who has 32 caps for England, saw his contract terminated at the Rec, but was this year handed a rugby reprieve by fellow South African Brendan Venter and will return to action next year for Saracens at Vicarage Road.
And while England's most capped player Leonard, speaking to promote the Aviva Premiership Rugby Schools Programme, admits Stevens may struggle at first after two years out of the game, he is adamant Venter can get him in shape in time for the 2011 World Cup.
"Matt may well play himself back into England contention sooner rather than later because he's a top player and really does have a great deal of ability," said Leonard, who was helping Aviva showcase their long-term commitment to English rugby.
"The only question remains if he'll be able to get back to the giddy heights of where he was two years ago as a modern, ball-running prop. Two years out the game is a long time, so it'll be intriguing to see how he improves and develops.
"But if someone can come back and establish themselves on the international scene after something like that, then it is Matt.
"And there's no better place to do that than at Saracens, under the tutelage of Brendan Venter. There's no way Brendan would take a risk on someone, he's not that type of person, so I trust his judgement. I wish him all the best as he's without doubt a great talent."