This is not the Wei-Yin Chen the Marlins signed

Wei-Yin Chen has been somewhat disappointing for the Miami Marlins to start this year. After a good first month of the season, he has struggled in May and June, culminating in an ugly win in which the Marlins put up 13 runs against the San Diego Padres but Chen still gave up four solo home runs for four runs in just over six innings. Over the past 30 days, Chen has put up a staggering 5.03 ERA and 6.11 FIP in six starts.

Why all the ugliness? There has been a subtle underlying change in his statistics that was first noticed last month: Chen was throwing lower in the strike zone.

That cannot be a coincidence. The Marlins are notorious for getting their pitchers to throw low in the strike zone and pitch to weaker contact. Chen, a pitcher who induces weak contact via his own approach, comes to Miami. Within seven starts, he is throwing lower in the strike zone than he has since he has gotten to the United States. Not only is Chen tossing a solid 16.3 percent of his pitches in the lower parts of the zone as compared to 14.8 percent of his pitches in the previous two years, but he is also seemingly abandoning the upper half of the zone. This year, Chen has only thrown 7.9 percent of pitches high in the zone and only 6.3 percent in that upper-in or upper-mid part that he used before to get popups. That is down from 12.4 percent and 8.7 percent respectively from 2014 to 2015.

Has this trend held up? Take a look at the location graphs for Chen’s fastball versus righties in 2015.

Compare that to those same fastballs to righties in 2016.

Data courtesy of FanGraphs

It is early in the 2016 campaign, and there is still time to change some of these trends, but the changes in the graph appear to be telling. Chen has spent a good amount of his career throwing middle and high in the strike zone. This is how he was able to dominate right-handed hitters in terms of inducing weak contact and beating his FIP-predicted ERA in the past. He came to Miami, a team that has previously emphasized working in the strike zone and getting ground balls low in the zone, and suddenly Chen is pitching more in the lower parts of the zone.

Last month, at least the ground balls were higher up. However, since that time, the grounders have run dry and Chen is now allowing too many pitches in the presumed sweet spot of the strike zone, where hitters can work their hard-hitting magic. In the last 30 days, Chen has only gotten grounders on 32 percent of his balls in play.

Meanwhile, he is suffering the issues with home runs that he has had for years, but he has not seen any benefit from one of his hidden marketable skills of the past: allowing pop-ups. Last year, Chen was among the lightest-hit pitchers in baseball, with an average exit velocity of 87.6 mph. This year, that is up to 90.1 mph. The percentage of hard-hit balls he has allowed so far this year is up 10 percentage points from last season. At the same time, Chen allowed pop-ups in eight percent of total plate appearances last season. This year, that number is down to three percent.

Pop-ups are near guaranteed outs, near-guaranteed outs that Chen has lost in his transition to this new location of his pitches. No one can claim at this point that this approach or result of locating lower in the strike zone is helping him. The question is whether this is indeed an approach designed either by the team’s pitching staff or a matter of loss of command for Chen. Before he signed with the team, there was some talk about the risk of running exactly this type of approach working high in the strike zone. From the preseason article:

Of course, a lot has been said regarding Jered Weaver here, and it should be noted that he has not exactly held up well. Neither has Justin Verlander, who was on the list as one of the most pop-up inducing guys in the game. Zimmermann just signed a large contract, but his previous season represents his worst of his recent career. Heck, even guys like Julio Teheran have not had great seasons recently. It is possible that running this type of skillset is actually higher risk and potentially more likely to decline. We already noted above that when Chen does get hit, he gets hit harder than the average pitcher; with even a small loss in command of that fastball, that balance of pop-ups and blasts out of the park could change.

Some of those guys listed also lost their stuff, making it harder to say that it was just a loss of command that did them in. However, both Weaver and Verlander started to struggle a little more visibly in their age-31 seasons, and that brought them from elite starters to average or worse pitchers. If Chen were to take a similar tumble due to early command loss, leading to more homers and fewer weak contact and pop-ups, that might take an otherwise above-average pitcher and make him potentially unplayable.

If this is an approach that either or the staff placed on him, it clearly needs to stop. Chen has to function and work the way he did as a finished product in Baltimore, and changing him now may only serve to muddle his arsenal and skillset. However, if this is associated with some loss of command and location ability, the Marlins may have a rough season (or more) ahead of them with Chen.