Look I think it all works together. Tight end blocking ability. Is absolutely zero. They just can’t set the edge. How is that on the line
It's both, left guard is a trainwreck, neither Williams or McGovern is more than mediocre. What's odd is that intially Jarwin was the pass catching tight end and Schultz the blocker, after Witten left Schultz showed he could catch the ball pretty well, but when Jarwin went down he had to go back to blocking, and I guess the league figured out his blocking style and has made adjustments.
But you can go with an average blocking tight end if the o-line is very good, which unfortunately isn't the case...