Celtic signed the centre-back from Rubin Kazan in the summer as the replacement for Kristoffer Ajer, who joined Premier League side Brentford.
Starfelt has been one of the certainties in the Celtic backline this season and has featured 13 times in all competitions in the ongoing campaign.
But Provan stressed that he has been worried about Starfelt since his first game in Europe when he got caught with a ball and looked suspect at the back.
He believes for the amount of money Celtic paid to sign him the Swede should have brought more authority to the Bhoys backline but at the moment, he looks far from being a sure thing.
Provan said on the Go Radio Football Show: “I just started worrying about him from day one, the first European game when he was caught with the ball over.
“They talked about Shane Duffy getting caught under the ball last season, Starfelt was exactly the same.
“I know he is right-footed playing on the left side but what was it, £4m they paid for him?
“For that money, you are looking for a player on who you can hang your hat on and who can go straight into the team and improve it.
“I don’t think he has necessarily done that.”
Starfelt is likely to be in the team when Celtic host Bayer Leverkusen at Parkhead tonight.