What’s cool about a situation where one group of players spends like 70% of their 5v5 ice time together is you can tease out the individual impacts from the WOWY. Or you can ignore the numbers and look at how the coach deployed that group and see how the percentage of time Barrie spent stapled to 97 increased dramatically after the first few games because it was obvious that he couldn’t cut it as an offensive driver or a decent defender and needed cherry minutes to have success.
I'm not an advanced analytics guy, but if Barrie contributes an incremental amount (A) in offensive production when paired with McDavid vs. when not paired with him (B), it doesn't matter if B < A. You should be looking at McDavid's production with and without Barrie to understand Barrie's incremental value to the team.
At the end of the day, the numbers are NOT the only factor. Team dynamic and culture is not necessarily quantifiable at the individual level. You want to keep McDavid and other team members happy and that trumps whatever minimal incremental improvements your fancy stats might drive.
This is a great value signing for a solid contributor. I expected Barrie would want $5M+, so I'm extremely happy he took a discount.