Johnson came up in the last page, so I figured I'd offer some info for folks who haven't been able to watch him at Michigan.
On the powerplay, he works off the left half wall. Unlike right-handed scoring threats like Ovechkin/Seguin, who drift wide looking for a one-timer, Johnson tends to drift in, looking to use his accurate wrist shot near side. He has good puck control and vision as well, which makes him a nice asset on the man advantage.
At even strength he's almost always lined up off Beniers' left wing, although he played a bit of center when guys were away for the WJCs. Personally, I think he's more likely a winger than center long-term. His offensive skill is his best quality, and I'm not sure he has the athleticism to carry the responsibilities of an NHL center without limiting his offensive upside. Granted, it can't hurt to give him more opportunities at center in either the NCAA or AHL levels to see. I just wouldn't want to see a Galchenyuk/Drouin situation where he's tried unsuccessfully at center for so long that it stifles his development.
Long term, I think there is real first-line, point-per-game upside here. That said, I think he's a guy you've got to be patient with. Personally, I'd envision that he probably needs another full year at Michigan, then probably a full year in the AHL, then he'll probably face some growing pains in his first year or two at the NHL level. But by the time he's 22/23 years old I think you're likely looking at a skilled offensive top 6 forward, maybe even a bonafide 1C.
If you're a BPA purist, Johnson should probably be pretty damn high on your board. I wouldn't blink if a team took him first overall in this hectic draft. For the Wings specifically, however, I think there are some complications unless you see him as a no-doubt center prospect. Johnson and Raymond operate best off the same half wall, so you'd either have to split them on different units or move one player to the opposite half wall (a good problem to have tbf, but something worth mentioning). More generally, if Johnson sticks at LW it leaves the Red Wings another year with a glaring hole in a top 6 center spot and two glaring holes at the LHD spot. Moving some of our excess wingers could alleviate some of that, but you're not getting a Power/Hughes/Beniers level D or C prospect in a trade around Mantha or Bertuzzi, so there is some opportunity cost to consider there.
Personally, I'm not sure I'd have the balls to draft Johnson top 3 over guys like Power/Beniers/Hughes who have similar upside at positions of greater need. But if we're picking in that 4-9 range again, I think Johnson should definitely be considered.