That's because the jury is still out on whether he has coached it out of him by giving him some extra responsibilities or if it's just that Milford is lazy and a dumb footballer that can't add anything new to his game. One of them we see on screen weekly and the other isn't public knowledge.
Wayne chose to offer it to him because he was touring the Storms facilities and holding it over the club. We need someone like Milford at the Broncos, don't get me wrong. He just needs to do something, anything! I honestly doubt that Bennett has told him to not run at all. He's just trying to add more to his game so it's not as predictable.
Speed might not be coached but it sure as hell can be forgotten. And in Milfords case it absolutely has been, in every part of his game. He can't even play the ball quickly. Bennett might have made an error recently with Taylor (which he got plenty of criticism for) but why does everyone keep making excuses for Milford? Bennett isn't the one coaching him to stare at the ref and slowly play the ball. He's not the one coaching him to drop balls left, right and centre. He's sure as hell not coaching him to pass to McGuire on the last or to slowly run sideways and hand it off to a forward for a hit up. He's not coaching him to kick it into the oppositions legs or to put on as much weight as he did last year and the year before. Where is his accountability? He's not an 18 year old kid anymore.