Just looking at the numbers, his ISO has increased over the past two years or so. He was normally a ~.110 ISO guy and the last two years it has jumped to ~.165. His BABIP is way higher now too so he could be feeling the extra speed to leg out hits from the test boosting.
It's not unusual for a 26 or 27 year to have an increase in power. Ian Desmond has an increase from the .120 range to .220 range this season.
