No no, let's continue.
If your partner is pooping back sitters over and over, there comes a point when it's worthless to stand in, so you might as well concede the point.
Standing at center of service line makes you a huge easy target.
At least when you stand ON the service line, you have a chance to get a lucky reflex blocking shot to, hopefully, neutralize the point.
Question of opponent hitting offensive shots, your partner barely defending with weak crap, so what are you going to do?