I'm guessing that the success of the Bunting -- Matthews -- Kase line had while Marner was out, as a reason Keefe is going back to what worked both ES and PP at that time.
Matthews goals 18-23.
Auston Matthews (23) - Assists: Ondřej Kaše (9), Michael Bunting (14)
Auston Matthews (22) - Assists: Alexander Kerfoot (18), Jake Muzzin (9)
Auston Matthews (21) - Assists: Morgan Rielly (24), Alexander Kerfoot (17)
Auston Matthews (20) - Assists: Ondřej Kaše (7)
Auston Matthews (19) (Power Play)- Assists: Ondřej Kaše (6), John Tavares (19)
Auston Matthews (18) (Power Play)- Assists: Ondřej Kaše (5), William Nylander (17)
Kase set up 2 X ES goals and 2 X PP goals in a span of a couple weeks, compared to Marner who has just 3 ES and 3 PP assists on Matthews goals over the course of a full season.