E5 hasn't dramatically increased his K% and he is not hitting a higher LD%. The things that stick out to me right now are his BABIP (.303 vs career .283) and his HR/FB (19.4% vs career 10.8%). While his HR/FB has fluctuated over his career there's nothing in his past numbers to suggest he can sustain that rate. Also while it might appear to an observer that he shortened his swing, his numbers don't indicate that he's somehow successfully changed his approach (which would lead to less K's or more LDs). He's a guy that posts a high FB rate, a high infield FB rate, and an average K% compared to major league averages. He's always been a guy that offers power with a lower batting average.
He should still offer power, though when his HR/FB regresses he may be a 25-30 HR guy and not the 40-50 HR that he's on pace for now. The best case, IMO besides just hoping he continues to get lucky, is that he has changed his approach and some of the contact being call FBs is borderline LDs and he could keep up a .280 or so average with that decent power. So he'd be a pretty good Util hitter in most 12+ team leagues (and some 10-team leagues), but not a guy you want starting for you at 1B in most leagues.
To answer the "is he for real?" question - if you expect him to hit .300 with 40+ HRs then he isn't and would need a crap-ton of luck to get there. If you expect him to hit .270+ or so with 30 HRs if he gets the at bats then yes I think he could be for real.