After making his club debut against Glasgow Warriors in 2010, McGrath, 25, has had to bide his time to establish himself at the RDS Arena with Cian Healy the incumbent loosehead for both Leinster and Ireland.
But in the light of Healy's recent injury woes, McGrath has become a fully fledged member of the front row for club and country, the prop impressing in Ireland's autumn international victories over South Africa and Australia last month.
Leinster turn their attention to European action this weekend, but will look to get their season back on track with inter-provincial clashes against Connacht and Munster before the turn of the year.
And Caputo feels Leinster fans are yet to see McGrath at his best.
"He's shown everyone how good a player Jack McGrath is," Caputo told the Irish Examiner.
"He's still only a baby, 25-years-old, and his best years are ahead.
"He offers you things that most players at that elite level of Test rugby don't give you. He'll consistently top the tackle count.
"He's very good when he carries the ball. He's very good on his detail and doesn't make mistakes."
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