But Rovers boss Grant McCann has one at hand to demonstrate the extent of the impact the Liverpool midfielder has had at the Keepmoat.
'We've been looking at his stats and his recoveries, in terms of winning the ball back for the team, and it's the best in the league,' McCann told the Free Press.
'I got sent it through from Adam [Ridgewell]Â the old analyst. He was telling me that Abu Ogogo at ShrewsburyÂ was winning 12 or 13 in a game last season.
'Herbie is already up to 16 or 17 so he's flying.'
It is fair to say that Kane was very much an unknown quantity to much of the Rovers public when his loan was confirmed mere days before the start of this season.
Expectations of aÂ player without a single minute of senior football experience to his name were low.
But it did not take many minutes for expectations to rise after he started Rovers' clash with Wycombe Wanderers.
With composure a player of his age and experience has no right to possess, Kane controlled the midfield, dictated the tempo, broke up play going one way and started it going the other.
And he has done the same in every game since.
Surely even a manager like McCann, who is exceptionally studious with his homework on players, could not have known how good the 19-year-old would be at League One level.
'When you're taking a loan, you've got to know a little bit about their background,' he said.
'I knew he'd come from a tough background in Bristol and that he was ready to come into the Football League because he's physically ready.
'What he probably surprised us with is how good he is in possession and breaking up play.
'In youth football there's no real emphasis, in my opinion, on winning the ball back.
'Coming from a team like Liverpool there is. That counterpressing and reaction, he's proved he's the best in this league at it.'
While it did not take long to see Kane's undoubted talent, concerns also quickly arose about the 19-year-old '“Â namely, will Rovers have any chance of extending the loan beyond January.
Whisper it quietly, but he looks a level above League One already so surely a Championship club would be willing to give him an opportunity in the second half of the season.
McCann is not letting such questions concern him currently and believes Kane's progress so far shows he is in the ideal place for his development.
He said: The last conversation I had with Liverpool is that they're very pleased with his progress.
'They obviously want Herbie to stay longer than these two years that he's got left there. I'm sure there is a conversation that Liverpool are going to have to have with Herbie about renegotiating his deal.
'But we'd love to keep him.
'I've mentioned it to HerbieÂ again and he's loving it here. Both him and Mallik [Wilks] are loving it here and would be happy to stay for a longer period.
'Unfortunately it's not in our hands, it's in Leeds and Liverpool's hands.
'If we can do a deal to keep them for longer we'll do it sooner rather than later.
'But at the minute we're obviously under the scrutiny of Leeds and Liverpool.
'Once we get the green light from them then we'll do it.'
With his quality both on and off the ball plusÂ several years of development still ahead of him, it is not difficult toÂ see Kane finding a career at Premier League level.
And McCann agrees with such sentiment.
But '“Â and perhaps thinking a little selfishly, for which he could be forgiven '“Â the Rovers boss has urged Kane to choose his next move with care.
'I think what he's got to be careful of, and I've spoken to him about this, is players often going out from Premier League clubs to the Championship and end up not playing,' he said.
'It's a huge step League One to the Championship. I think that step is bigger than Championship to Premier League '“Â that's how big a step I think it is.
'If he goes out and doesn't play, he's going to go back into the Under 23s at Liverpool.
'I think Livepool would be happy for him to stay here, and Herbie would be.
'He's played, what, a dozen gamesÂ in the Football League.
'It's incredibleÂ the way he's taken to it.'