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Amed Rosario Batting

Amed Rosario’s Plate Discipline Lacking

One of the bright spots looking forward to the 2018 season is Mets shortstop Amed Rosario. Just 21 years old, the slick fielding ‘Rosy’ is likely to be heavily featured in ticket promotions this winter.

Rosario’s glove was not flawless in his brief rookie season. His errors occasionally cost the Mets and even angered Jacob deGrom once. He showed a tendency to be nonchalant on easy plays. Still, he was a huge defensive upgrade over the previous Mets playing shortstop. He should be a plus defender for a long time to come.

Free Swinging

Where Rosario most needs improvement is at the plate. He is extremely aggressive, swinging at just about everything. He was that way in the minors and has continued the trait in the big leagues. Here’s a heatmap of his high swing percentages in the majors.

Amed Rosario Swing Percentages 2017

While still in Las Vegas this year, Rosario had a 5.4 BB% and a 15.8 K%. The strikeout number doesn’t look too bad. But Amed got worse as the minor league season went on. In his first 44 AAA games he had a 13.3 K%. But in his final 50 AAA games his K% climbed to 17.8%. It only got worse when he was promoted to the majors.

In 170 big league plate appearances, Rosario walked 3 times and struck out 49 times. There’s no way to describe a 1.8 BB% and a 28.8 K% as anything but ugly. There is some worry on the team that he’ll never learn to take pitches. GM Sandy Alderson talked to Amed before the season ended. As quoted in

In our conversation, basically what I said is that, if he gets the strike zone under control, he could be a superstar. I think that’s the impression that he’s made. Not that he’s a ready-to-go All-Star player, but he has the tools and the potential to be an outstanding player.

Amed Rosario’s Plate Discipline

Why any pitcher threw Amed a strike this season is unknown. Rosario had a 45.5 O-Swing%, which means that he was swinging at nearly half of the pitches he saw that were actually balls. As a comparison, Brandon Nimmo swung at only 17.0% of pitches out of the zone, sixth best in baseball among those with at least 100 plate appearances. The league average was 29.9%. Rosario was the fifth worst in all of baseball with 100 PAs at swinging at balls out of the strike zone. His strikeout rate closely tracked his chasing of pitches out of the strike zone as this chart shows:

Amed Rosario Strikeouts and OSwing 2017

Hope for 2018

When the Mets promoted Rosario, the team said that he would receive days off since he was going to set a new career-high in games played. Combining minor leagues and the majors, he played in 140 games this year, passing his previous high of 120 in 2016. Despite possible fatigue, Rosario hit .262 after August 31st.

It took three years for Jose Reyes to have his break out season at age 23. It’s unfair to expect Rosario to reach his maximum potential for several more years. Until then, he will stay in the lineup due to his athletic ability, defense and speed. Amed possesses raw talent. He needs to learn plate discipline and pitch recognition.

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