Turbin gets north and south faster than Michael does. He's never going to be Lynch, but lately he's trucking the first defender and at least getting extra yards after contact.
As for RIchardson, like others have said, the explosion will come as the game slows down. When he doesn't have to think about what the right route is, what the defense is doing, how deep/fast to run the route, then he will play a ton faster. It's typical of guys on defense: when the can just react and not think, they play faster.
I've never plyaed WR, but playing LBer, sometimes our coach made us run simple routes to not only get a better understand of what the offensive player does, but also to get used to breaking on the ball, getting timing down and actually catching the ball.
It's amazing what WRs have to do to be truly good. You have to know what route, in what situation to run, as it will change depending on what the defense shows you. You have to know how deep certain routes go, and whether to option out of it based on what (if any) zone look the defense is getting to you. Imagine running a 10 yard out (breaking towards the sidelines). You have to have your footwork down exactly: on that 12th step (or whatever your stride is) you need to be on your left foot (if on the right side of the offense and breaking right) so you can explode into that break. If you get wrong footed, you have to stutter step it, run an extra stride, or otherwise change that route. This causes you to slow down to think about what you need to do. Stutter stepping is a tell that good defenders will read.
Baldwin is such an underrated WR because of this. He's explosive out of his breaks, even though he isn't that fast, and it gets him open. He has those routes DOWN exactly, and it shows. Stevie Johnson, when he was giving Sherm and Revis trouble in Buffalo, is the exact same way.
Add all this in to WIlson's scrambling ability, and you have a lot to learn. Richardson will be fine. IMO he's ahead of the curve.