To me part of the frustrating part is Connor always seems to do well away from Scheif. Had his best season playing with Dubois...Ehlers is definitely elite at zone exits, but he also seems to turn pucks over at the offensive zone blueline. I'm not sure about the frequency, but I do notice it when it happens because coaches HATE turnovers at both bluelines because of the counterattack that they cause (the resto of the team is moving in the wrong direction)
As for the scoring rates, I'd be curious to see how much the gap narrows once stregth of competition is controlled for. It seems obvious that Ehlers makes the top line better vs Connor, but usually ehlers is either being played with Schief and Connor or Connor is injured. There haven't been many instances where they've swapped spots... but Connor Monahan Perfetti was a great line in the limited minutes they got when Bones reunited ESL
Some of these stats arguments can be pretty nuanced and complicated. This one was frustrating because it seems pretty straight forward, and Bowness just didn't see it the same way. And the results turned out the same again.