The overwhelming consensus is that Flores's bat will translate to the major leagues eventually. What is holding him back from reaching his offensive potential in his short career so far?
Flores has shown little plate discipline, which is common for young players, walking well below average and swinging frequently at pitches out of the zone. He has never walked much in the minors, so it's not likely he'll start in the big leagues. He'll need to maintain a high average in order to be productive at the plate, by putting the ball in play and by making good contact.
One positive for Flores is that he has drastically improved his strikeout rate from last season. He makes a lot of contact, even on pitches out of the zone, so he's succeeding at putting the ball in play.
The problem so far is the quality of that contact. Flores is hitting some line drives, which is a good sign, but he's also hitting a lot of fly balls. Fly balls aren't conducive to a high average in general, and Flores just doesn't have the power necessary to turn those into hits. While he is still developing strength at only 23 years old, his build and his minor league performance suggest he'd be better served by keeping the ball on the ground.
With a knack for making contact and relatively little natural power, Flores should look to Daniel Murphy as a model for success. Like Flores, Murphy keeps his strikeout rate very low by connecting with a lot of good pitches. Flores can learn to adjust his approach to do a better job of fouling them off (like Murphy) instead of putting them weakly into play. This should result in more hard-hit balls and a higher average. More line drives (and harder-hit line drives) will also result in more extra base hits, of which Flores has only 12 in 240 major league plate appearances.
Now that Flores is seeing consistent playing time, he should have the opportunity to tweak his approach more effectively. With some minor adjustments, he could be on his way to meeting, or at least nearing, the high expectations that have surrounded him since he was just 16.