Willis isn't an NFL QB yet but Tannehill is hurt and they didn't have a choice. They were probably only working with about 20% of their passing plays in the playbook
I think it's that their D is playing really well and they're trying to protect their rookie QB. He wasn't supposed to play this year. He was a developmental pick. They're honestly probably playing with a significantly pared down playbook.
It looks like that but I think he just saw all the action coming his way and was trying to get out of the play and good grief there's somebody over there too why has this QB thrown a ball into the entire opposing secondary?