I'm not sure if thats true or not (I'd lean towards it not being an issue) and that's not a good enough excuse if you lose this series. If you swap him and JWill this is over in 5 (assuming KD is healthy although he has been the past couple seasons). As far as chemistry I'm not seeing anything that Durant wouldn't improve - y'all have taken terrible shots all series.
Their salaries aren't close to matching though, so I'm not sure how that trade works anyways.
As far as JWill goes in general - I get he's a good defender and he stuffs the stat sheet pretty well but his shooting splits in this series are straight up inexcusable so far for a championship 2. He's had misses this series where it's like he's afraid of the basket. I don't know if that gets better or not but as of now I'd be hesitant about giving that guy a max contract. Even in the regular season his TS% was below league average. This might just be who he is.
We'll see what G7 brings - maybe he has 30 and y'all cruise.