Manny Machado is the best player the Orioles have had in quite some time. He's so good that not only has he been able to improve some part of his game each season, but he's young enough at 24 to leave you wanting, and even expecting, more. That'll stop at some point, but we're not there yet.
Despite knee injuries that ended his 2013 and 2014 seasons, Machado was still able to increase his production at the plate in each of his first four major league seasons:
2012: 97 wRC+
2013: 102 wRC+
2014: 111 wRC+
2015: 134 wRC+
In 2016, Machado was well on his way to increasing his offensive production for the fifth straight year. In the first half of the season, he posted a wRC+ of 147 and was tied for fourth in position player wins above replacement with Jose Altuve (4.3).
But Machado fell off in the season's second half. He posted a 108 wRC+ in that span, which isn't terrible, but not what's expected of someone with Machado's talent. And although he wasn't alone in his second-half struggles (and many teammates performed far worse), his dip in production did drop his overall wRC+ to 129 and ended his extended stretch of improvement
So what happened? First, he didn't walk as much in the second half. Last year, Machado walked nearly 10% of the time. That was far and away the best of his career, and it also coincided with him transforming into a power hitter. His 35 home runs in 2015 were 23 more than the previous year. But in the first half of 2016, he walked 8% of the time, and that dropped to 5.6% in the second half. That's also factoring in nine intentional walks in 2016. In 2014 and 2015 combined, Machado was intentionally walked four times.
Machado also wasn't nearly as fortunate on batted balls in play in the second half. After posting a BABIP of .346 in the first half, that mark plummeted to .268 in the second half. He ended the year with a .309 BABIP, which is nearly identical to his career BABIP of .310.
Let's get back to plate discipline. Oddly enough, while Machado walked less, his strikeout percentage was nearly identical: 17.3% in the first half; 17.2% in the second half. Diving into some Brooks Baseball data, Machado actually swung less in the second half. He offered at about the same number of hard pitches (about 50%), but he swung about 3% and 4% less, respectively, against breaking and off-speed pitches. His whiff percentages were about the same for hard and breaking pitches, but he cut them almost in half against off-speed pitches.
Overall, Machado's plate discipline numbers look more like his 2014 numbers than his 2015 ones. In 2014 and 2016, he swung about half the time. In 2015, that number was at 43%. That year, he also chased fewer pitches but still made better contact on the ones he offered at outside the zone (inside as well).
Weird things happen over entire seasons, let alone parts of a single season. I wouldn't say there's anything that's cause for concern. Posting a wRC+ around 130, when combined with the value that Machado's outstanding defense at third base provides, might not make you the best player in baseball. But it gets you extremely close to the top. Besides, Machado may indeed have the skills to climb that next step.