By Dan Bernstein–

CBSChicago.com senior columnist

(CBS) Cubs rookie Kris Bryant has put up solid numbers at the outset of what promises to be a successful big league career. Through his first 63 games, he has posted a slash line (BA/OBP/SLG) of .278/.383/.474, adding up to an .857 OPS.

What’s striking, however, is that he’s proving to be an entirely different player under the sun than he his under the lights. And the diurnal version of Bryant is pretty awful.

In 24 day games, he’s batting .226/.353/.357. That’s a mere .710 OPS that includes just two homers and 36 strikeouts. For a power-position player, that qualifies as barely replacement level.

But like some kind of movie monster, Bryant emerges at night to wreak havoc on the unsuspecting townsfolk, raking at a clip of .307/.400/.540 in 39 games, good for a .940 OPS and a home run for every 5.75 strikeouts — nearly three times better than in day games.

These are small samples, of course. Just noting such stark disparity at this point.

Bryant has had other daytime issues, too, having to come out of a game last month with what the team called “dehydration” and then exiting Thursday afternoon with “flu-like symptoms.”

Being a Cub still means playing often at 1:20 p.m., sometimes right after a game the night before. As dedicated and professional as Bryant has been since being drafted two years ago and rising through the minors, it’s reasonable to expect he will make the proper adjustments, acclimating himself to the demands of the major league schedule.

Dan Bernstein is a co-host of 670 The Score’s “Boers and Bernstein Show” in afternoon drive. Follow him on Twitter @dan_bernstein and read more of his columns here.