But head coach Alan Solomons has seen enough to hand the youngster a start against Connacht on Saturday evening.
The youngster is normally a fly-half but will wear the No.15 shirt in Galway and lock McKenzie is excited about the youngster's potential.
"Blair is straight out of school, but he is one skilful player and I think a lot of hopes will be pinned on him in the future with Edinburgh and Scotland," McKenzie told the Scotsman.
"He has to learn his trade and really develop and I think he is in the right place to do that. We will look after him now that he gets his chance and on the confidence scale of things he is up there. He has great belief in his own ability.
"He has got all the tools and he is a good, down-to-earth boy."
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