I think the author has been throwing in a bunch of references to the relative immaturity of Ash's team to give him some room to work with for future growth. Didn't he manage to take down one of Lance's less experienced team members during his training arc with him? I'm guessing Metagross is supposed to be pretty outstanding even among Champion-class pokemon. Steven's line about a win being impossible at this point irked me though. Like Hugplx said, that's pretty much the worst way of getting your point across. Ash isn't starting out as some disrespectful hothead, so demonstrating what he should be aiming for would have been a better use of time than just crushing him.