I see a 2.5% increase in FB rate, small improvements to PD stats that probably don't support a 4-5% drop in K-rate, and similar contact quality to what he did in 2016.
If I'm looking for a driver for his big 2017, the 0.392 BABIP - 72 points higher than the career 320 mark he had entering the year - looks like far and away the biggest reason for his success.
His steamer projection (111 wRC+, league average player) seems pretty reasonable to me.