So from watching some DEL games, here are my new impressions of Seider:
Offensively he's better than I thought at the draft. He jumps into the rush really well, and is always looking to. He reacts to turnovers really quickly, but rarely puts himself too far out of position looking for offence. He's always ready to go but doesn't force it. Skates well through the NZ, and can carry the puck or hit a teammate up ice with a good pass. I think controlled exits/entries are going to be big strengths.
In the offensive zone he tends to hang pretty high on the blue-line-mostly coming deep on zone entries or to stuff a breakout along the boards. He'll walk the blueline or drift into the high slot to find a good shooting angle, but he could stand to try more. You can tell he likes to contribute offensively but takes his responsibilities seriously.
His defensive game is less developed than I thought though. He is strong and skates well enough that he doesn't get beat easily in one-on-ones, furthermore he clears the front of the net well. He has the bad habit a lot of young d men have where he gets sort of lost in between his net and the boards too much. He'll abandon his coverage to try to hit someone or will pursue a forward to the wall, but get caught deciding whether to retreat back or pursue if they pull away. I think this is actually the weakest area of his game right now. He's even better at getting involved in the offense than I had thought, especially on the rush, but he's not the steady, already defensively developed TWD I thought either.