Here's the write-up on Sanheim from the ISS, who ranked him 30th in this draft:
Phenomenal World U-18 performance on both sides of the puck for Sanheim throughout tournament. Truly elevated his game to another level and stepped up as the defensive leader while showing a good offensive skill-set. Sanheim is the type of player that is very appealing at first glance because of his size and the aestethics with he moves around the ice. He joined the Hitmen early in the season and he took the opportunity and ran with it. He is still very raw but has good range and shows decent agility and lateral movement mechanics. He controls space well against the rush and makes good decisions with the puck in his own end. Sanheim’s offensive capabilities grew as the season went on and his confidence around pucks became stronger with every game.
NHL Central Scouting had Sanheim ranked 53rd (!) amongst North American skaters in this draft. He's not a very physical guy and he's not going to be an NHL player immediately, as he's still very raw. But by all accounts, Sanheim has a ton of upside, and Flyers WHL scout Mark Greig has likely seen him play a ton of hockey. To go at least 13, if not 20, players off the board at this stage of the draft, they'd have to be pretty comfortable with this guy.
There are indications that his stock was rapidly rising this year, though. And if Greig has seen him a lot, maybe it's just that the Flyers simply recognized that before other teams. He was really all over the board: 53rd on Central Scouting, but as high as eight on Craig Button's board at TSN. McKeen's had him at 15. All over the dang place.
Hey, the Flyers have gone off the board before. Samuel Morin was off the board a year ago. Scott Laughton was off the board two years ago. They know what they're doing when it comes to amateur scouting, and we truly have no reason not to trust them in this department. The draft is one of the Flyers strong suits.
Give Sanheim a follow on Twitter at @sanheim17.