By: Jason Ferrie, Sports Talk Philly Columnist 
The Philadelphia Phillies enter the All-Star Break with the MLB's worst record, which is a pretty good indication of how disappointing the 2017 season has been at the major league level. Though he hasn't been the most disappointing player, 2016 National League All-Star Odubel Herrera just completed a pretty rough first half of the 2017 season, coming off of an offseason where he signed a long-term contract. But should we have been able to predict the decline that Herrera has gone through thus far?
Bench coach Larry Bowa recently told 97.5 The Fanatic's Mike Missanelli that he thinks advanced analytics are they’re overused in today’s game. While I do agree that they are fed to players more than ever, they’re very useful, especially when trying to predict the future. One case we can look at is Herrera, who has been in the spotlight for his performance and actions at times this season. If we look at the numbers from the time Herrera broke into the league, it turns out that his down year may have been more predictable than we thought.
Herrera has still managed to be an above-average defender in the outfield, which is the reason he has still been of value to the Phillies this season. His bat, on the other hand, has let him down.
Using his batted ball profile from seasons past, Herrera has always been a candidate to put the ball on the ground. In fact, Herrera has posted three-straight seasons with a groundball rate greater than 45-percent. As I've said when breaking down Maikel Franco's struggles, groundballs aren’t the best way to be a productive hitter.\
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In 2015 and 2016, Herrera managed to be better than a league-average hitter on offense despite the high groundball rate, but that was due to very high batting averages on groundballs in play. In 2015, Herrera had the second-highest batting average on groundballs put in play at .355. That season the league posted a .236 batting average on groundballs. Herrera also managed to post a 103 wRC+ on groundballs, which is absurd. In 2016, Herrera posted the 14th-best batting average on groundballs in play at .335, while the league managed to hit just .239 on groundballs. Of course, there are players who hit above league average on groundballs each year — but over 100 points better than league average should highlight one as a regression candidate.
Turn the page to this season and we find Herrera with a 77 wRC+ heading into the All-Star Break. In the two seasons prior to this, Herrera finished with at least a 110 wRC+ for the season. But remember, in the past two seasons he significantly outperformed the entire league when putting the ball on the ground. To this point in 2017, Herrera has put the ball on the ground at a similar rate and witnessed his batting average on groundballs drop to .232, which is in line with the league average on .241 in 2017.
It isn’t as if he is losing hits to the shift, either. Per StatCast data, Herrera has been shifted just four times on groundballs this season and just of those four at-bats ended with an exit velocity greater than 80 MPH.
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For what it’s worth, Herrera is also generating a lower exit velocity on groundballs this season, averaging 83.8 MPH, compared to 86.2 a season ago. I suppose there is a chance he’s lost a few hits due to diminished exit velocity, but that isn’t the main reason for his struggles. For two consecutive years, Herrera has outperformed the league in batting average on groundballs and it’s finally caught up to him this season.
Interestingly, on line drives and fly balls, Herrera has been great. When putting the ball in the air this season, Odubel Herrera has a 127 wRC+ and .905 OPS. When he hits a line drive, his wRC+ jumps to 333 and OPS shoots up to 1.611. These numbers shouldn’t be a shock, though, as baseball is shifting toward keeping the ball off the ground.
While some believe that advanced analytics are making their way into the game too much, it is important to be use for situations like this. We can acknowledge that Herrera had two good seasons in a row while also noting that we should have viewed him as a regression candidate based on his success while hitting groundballs. It may seem shocking that Herrera is struggling to this point in the season, but maybe it was something we should have been cautious of all along.
