I've never put much stock in WS and this proves my skepticism.
Your skepticism is warranted. I've never been all that taken with WS either.
All this study does is point to the possibility (based on two questionable assumptions: that WS represents what it claims to represent, and that the predictions for 2013-14 WS are based on a solid methodology) that the Jazz will be somewhat better than most forecasts expect and that the bench will be a strong reason for this surprising strength.
We'll just have to see what happens.