Mark forces forehand. Feet in wide and athletic stance. Handler holds disc ready to throw forehand. Mark's hand is actively stopping the shown throw to prevent throws to the break side. They don't need to stop the throw going to the open side, just the inside throw to the break side.
Cutter begins their cut
Handler can make an inside forehand to the breakside. If the mark is getting beat by the handler without even pivoting, they need to better position their body and their hand to block that throw. Their hands should be in front of the disc wherever it goes. Can also add hand movement to further obstruct the thrower.
OR
The handler in this drill is allowed 1 pivot to their backhand. As the handler pivots, the mark needs to shuffle their feet to reposition their body and again their hands must stop the shown throw. Do not LEAN. This puts you off balance and a good handler will punish you.
Handler makes outside and around backhand throw to the breakside if possible.
Rotate. The Mark goes to the back of the cutter line. The handler is now the mark. The cutter joins the handler line