Watch the replay.
Even if the receiver was to run the route where Mills threw the ball too, Mills telegraphed the play from the start.
Two guys were to converge on the receiver.
Mills has got to know this.
Plus he knew, as the QB, that the INSIDE route will draw the other safety to the offensive left (the middle of the field).
The corner route to the right will be in one and one.
Watch the beginning of the play, you can see the way the play was designed that no. 15 will be in one on one one the right side against Cover 4.
I really don't think it's a good read nor a good execution of the play by Mills.
In a nutshell, if the QB sees a double team, he needs to move on to next read.
Mills didn't even seem to acknowledge the double team.
A good QB will manipulate this play as it was to draw both safeties to that side as what happened there butqqq00 throw the corner route to the opposite side (his right).