D1 is going at ~50%; they are not trying to make a play on the first throw
The point is to have D2 realize where the dangerous/easiest throw on the field is, and take that away. Defensively, we would rather have the offense throw a loopy pass over the stack that we might be able to defend elsewhere, than a short quick unmarked throw into space that no-one can stop.
As a defender, listen to the up call and find the disc.
C can make cuts at any time, so don’t necessarily follow them or you might get thrown off by fakes.
Get into the space they are trying to attack, you are playing underneath so you have the advantage of having a better angle/shorter line.