Boston needs additional shooters (Marcus Morris, Jaylen Brown, Horford are shooting the ball well enough to offset Kyrie's struggles yet their FG% is below average). Kyrie %'s will go up once they get more shooters because those guys might be shooting above 37% from deep but they're mostly open because opponents don't respect them thus the paint is packed (poor gravity score).
Another way to look at is his struggles simply might be due to his increased effort on defense impacting his overall efficiency on offense. He looks winded by the 2nd quarter but he's never had the best conditioning (He certainly needs to tweak his diet and fitness to take the next step IMO). I've never seen a star/superstar averaging 31.1 mpg yet looking so tired even though he has multiple ball handlers and an excellent system (more off ball movement could be a factor on offense as well).
The year Curry won his first MVP there were multiple players who had better raw numbers but his shooting splits were amazing AND his team won 67 games. Russ won simply with stats, so Kyrie will have to equal Curry or Rose level of team success while reaching reaching their efficiency.
2014-2015 Curry - 23.8, 7.7, 4.3 ( 48.7, 44.3, 91.4)
2017-2018 Kyrie - 20.3, 5.3, 3.2 ( 42.9, 31.9, 88.1)
2010-2011 Rose - 25.0, 7.7, 4.1 ( 44.5, 33.2, 85.8)
Those numbers are not good enough this year against Harden
2017-2018 Harden - 31.8, 10.1, 4.8 (45.0, 39.8, 86.0)