What's the difference between a Taylor Hall or a Tyson Barrie if the on-ice result is the same though?
As I said: one bumps other forwards down the depth chart, the other doesn't.
I have no answer for your initial question because I don't know how to respond to the suggestion that Barrie has no impact on McDavid's production. I have no way of isolating his impact, but I tend to believe that many of Barrie's contributions are positive and not just a direct result of McDavid's work. I don't see Darnell Nurse's game thriving in the same manner playing next to Bear as a partner.
Maybe the impact isn't the same but that's not really the question. The question is: does spending $5M+ elsewhere on the roster have enough of an impact to offset what is likely to be a marginal decrease in production from the top end of the roster? I think that's a no-brainer. McDavid is going to be at his most productive over the next two to three years, you don't need to overegg the pudding there with a guy who can't produce anything close to the same away from 97 and who is at best a question mark on the other side of the puck.
There's a lot of truth to the fact that McDavid generates his own offense. This is the primary reason why I'm hesitant to throw money and term at a scoring winger when realistically that role is the perfect carrot for emerging prospects.
I think the idea here is you have a vet winger on each top line, an elite C and an emerging young player on the other side.
You could also forgo the top end winger idea and spread the cap savings across the bottom six. Those are choices you have that you don't when you're paying a lot of money to Barrie.
You're bound to see a lot more value spending cap dollars on players suited for third and fourth line role instead of assuming the trickle down offense theory works. When a team like Tampa Bay is willing to spend significant futures on players like Blake Coleman and Barclay Goodrow, I'm fairly convinced that effective checking line players are actually quite difficult to obtain
It's easier to acquire those players when you're not paying premium dollars for marginal increases in top end production is my point.