You have your view on this. My view is that Propper is both quicker than Stephens, but also moves the ball quicker. I do recognise that this is required given that he plays slightly higher up the pitch, and that both play the ball backwards, and that Stephens' passing success rate will be higher...
He played on the left when he came on. Knockaert was on the right. March even set up Knockaert for our equaliser from the left. As A1X says, he was great against Millwall on the right when he came on the other week. I do wish he'd take players on more.