IMO, anyone that tries to analyze the Leafs "first" pairing doesn't know anything about the Leafs.
Last year Reilly played so many minutes PP and relatively few as PK....does that make him a "first" pairing. Zaitsev and Hainsey played lots....lots of PK together but hardly any all at even strength. What were their magical "numbers". It's a silly, meaningless system , that the ill informed use.

Rielly was your TOI all situations leader, followed by Zaitsev and Hainsey. 5v5 was the same as well...top 3 Reilly, Z, and Hainsey

5v5 per Game Rielly was 19:27 and Gardiner was 19:14. I think its safe to say Rielly was played as the leafs top pairing Dman all last year. Babcock leaned heavily on Zaitsev and Hainsey for the PK, but Rielly was still 3rd in Total SH time out of the Dmen.

Barrie should get a lot of minutes now on the leafs, wouldnt be shocked to see Riellys number go down with Muzzin and Barrie in the mix, Ceci will be leaned on heavily for PK though, but wont see as much 5v5 and probably not even a second of PP time

yes please please please please please have Ceci on the top pair

the top 2 D pairs will probably both act as the "first" pair. However with the 3rd pair shaping up to be pretty terrible both of those lines will probably need to play 25-ish minutes a night, and that's where it's gonna suck to have Ceci in the top 4.

Exactly