A check-up with Gregory Polanco

Back in March, I wrote an article for Batting Leadoff, examining the optimistic projections surrounding Gregory Polanco. Specifically, the ZiPS projections on Fangraphs forecasted Polanco to be worth 3.2 wins above replacement. Looking deeper, I found that both the Steamer and ZiPS projection systems considered Polanco a slightly above league-average hitter, with ZiPS a little bit more optimistic.

The real difference in forecasts between the two systems came on the defensive side, where ZiPS saw a well-above league average outfielder and Steamer essentially saw Justin Upton's glove. At the time, I concluded that Polanco's prowess in the field would decide whether he became a star in short order or a fourth outfielder. Now, with the season in its home stretch, it seems like a good time to go back and re-investigate.

Comparing Polanco's fielding statistics to last season's numbers, it is apparent that he has improved quite a bit. The following chart shows his UZR and DRS, two of the best metrics for evaluating defense, from last season to this season.

Both metrics agree almost perfectly that Polanco has improved markedly as a fielder. This improvement seems plausible; now 23 and in a regular starting role, it stands to reason that Polanco would begin to live up to his many physical gifts in the field. In addition, Polanco has been his usual excellent self on the basepaths. According to Fangraphs, Polanco has accrued 4.7 runs above average as a baserunner, good for 13^th in the majors.

Surprisingly, the area which Polanco has yet to live up to the projections is on offense, where he has produced at a rate 3 percent below league average. This is not to say that Polanco's production at the plate has been surprising; as a 23 year old receiving regular at-bats in the majors for the first time, he has acquitted himself well enough. However, both Steamer and ZiPS projection systems forecasted better for the young outfielder.

It would be premature, however, to christen his season an offensive disappointment. Polanco has made strides at the plate, especially in the second half. The following chart shows Polanco's swing rate on different pitches in the first half versus the second half (All data from Brooks Baseball).

Obviously, the halfway point is an arbitrary cutoff; it is quite possible that any adjustments Polanco made were put in place before the break, or even after. With that being said, there is a clear trend in the table. Against fourseam fastballs, sinkers, changeups, and sliders, Polanco has drastically increased his swing rate in the second half. The result: a wRC+ of 121 in the second half, versus 81 in the first half.

It is unlikely the increase in offensive production is due entirely to Polanco's swing rate. The simple accumulation of repetition often works wonders for young players. However, Polanco's increased swing rate has coincided with a number of positive outcomes at the plate.

Polanco's walk rate has dropped, from 10.1 percent in the first half to 6.8 percent in the second. However, his strikeout rate has dropped slightly as well, from 18.8 percent to 17.7 percent.  So while he is swinging more, those extra swings are not necessarily spelling more strikeouts.

In addition, when Polanco has made contact, he has hit the ball with more authority. His hard hit rate, according to Fangraphs, was 27.7 percent in the first half. That number has risen to 34.3 percent in the second half. As is expected when hitting the ball harder, Polanco's power numbers have improved as well. In the first half, he posted an ISO of .100, a damning figure for a corner outfielder. However, in the second half that number has improved to .156, which is much more palatable. Polanco's BABIP has skyrocketed in the second half as well, from .289 to .352. While part of this increase is perhaps due to luck, much of it can be accredited to Polanco's increased hard-hit rate. The former top prospect also cut down his groundball rate from 48.7 percent to 42.1 percent and raised his flyball rate from 32.1 percent to 37.2 percent. Ground balls go for hits more often than fly balls, so a BABIP increase despite an increase in the batted ball type that goes for a hit less often lends more credence to the idea that Polanco's quality of contact has increased dramatically.

Coming into the season, it appeared that Gregory Polanco was poised to make the leap and become the third star in what may be the league's best outfield trio. Defensively, Polanco has made huge strides this year, and he was already an excellent baserunner. Though the offensive numbers look somewhat unimpressive in the aggregate, closer examination reveals major improvement in the second half, potentially due to a more aggressive approach at the plate. Additionally, even considering the early offensive struggles, Polanco has still been worth just over 2 fWAR this season.

As the leadoff hitter and an important cog in the outfield of a likely playoff team, the continued development of Polanco's offensive and defensive game bears watching in the future. For now, at least, it appears that the young player is making the right adjustments.

Tom O'Donnell is a contributor at Beyond the Box Score. He is also a junior at Colby College. Follow him on Twitter @Od_tommy