Washington Nationals’ infielder Starlin Castro hopes success with new launch angle will carry over into 2020

Yes, the Washington Nationals had a sluggish start to the offseason. That can easily be forgiven given that they were, you know, winning a championship and celebrating hard.

That meant that GM Mike Rizzo had ground to make up and boy has he in the new year.

Among five signings in five days was a player that seems to have fan opinion divided in Starlin Castro, who officially put pen to paper on a two-year, $12 million deal on Tuesday.

On one hand, Castro is a career .280 hitter who has only hit below .265 once in his career. He also hit 22 homers with 86 RBIs, playing all 162 games for a poor Miami Marlins team who call a pitcher-friendly park home, so he could be a good change-of-scenery candidate.

One the other hand, Castro is seemingly allergic to walks and doesn’t slug a whole lot, evidenced by his career 98 OPS+. Last year he was a tick below that with a 94 OPS+ with a measly 4.1 walk-rate and was only 90th among 135 qualifiers in slugging percentage.

With some interesting stats on both sides, who’s to say which of the above opinions is right?

Actually, the second one is right. Despite excelling in some old school metrics, Castro, with his lack of walks leading to less time on base, has overall been basically a league-average hitter in his career — with his 98 OPS+ indicating he’s been 2% below league average.

However, whichever opinion you side with, there is a nugget that should interest both sides.

Following a pretty poor first half of the season in which he slashed a dismal .245/.272/.336 with just six home runs, Castro decided to make a slight tweak to his swing.

“I just changed a little bit,” Castro said on a conference call with reporters last Tuesday. “I think I hit too many balls into the ground and I opened a little bit my front foot.

“And I just said to myself ‘OK, I’m just going to try to hit the ball in the air. No matter what will happen, no matter what reason is going to be. It’s been tough already in the first half.’

“And that’s one of the things that I did, I just said, ‘OK, let’s pull the ball. Let’s try to do launch angle, try to hit the ball in the air, and let’s see what happens.’ And it happened in the right way and with really good results.”

Good results might be an understatement from Castro. In the second half, he posted an impressive .302/.334/.558 slash line, hitting 16 of his 22 home runs in 14 games fewer.

Yes, his walk-rate was still a pretty abysmal 4.3 in the second half, but because of the power that he was able to unlock, he posted a much more healthy 129 wRC+ after the All-Star Game.

Looking at the film of his swing at the start and end of the season, it’s pretty easy to spot the changes that he made.

First off, let’s take a look at an at-bat of Castro’s in March against the Colorado Rockies...

Courtesy of Baseball Savant

Looking at this swing, you can see that he started very square to home plate and even landed in a similar position as he set himself to swing. That led to him not generating a whole lot of torque as he comes around to make contact with the ball.

And then when he did go into his swing, you can see from the follow-through that his swing plane is fairly flat, a theme for him during the first half, which led to too many ground balls.

However, if we compare that to a home run that Castro hit off of Junior Guerra in September, we see a marked difference in his swing mechanics...

Courtesy of Baseball Savant

The obvious tweaks are in his pre-swing position and as his front-foot lands, both becoming more open. Doing so gives his much more torque, as evidenced by the fact you can now see the name on his back when his front foot lands, which you couldn’t on his early swing.

However, the most important adjustment was that he was able to start getting the ball in the air more. In this swing, when he makes contact with the ball, you can see the bat angled further down and the follow-through is also less flat, leading to the fly balls that he was after.

This tweak to his swing and production caught the eye of the Nationals’ front office...

“We did see a change in him,” Rizzo said at Winterfest on Saturday.

“We saw him play a million times when we play Miami in Spring Training, and we play them in the season a lot. We did see a change at the back end of it.

“Kevin Long and I discussed it, we’ve talked about Starlin, and Davey recognized it, and when Davey and I talked about bringing him on, Davey had him, he loves him and he thinks that he’s got a great chance to take off and be really good for us.”

This adjustment is also similar to the one that Brian Dozier made in 2019 after his slow start and you can see the effect this change had on Castro’s launch angle the rest of the way...

Courtesy of Baseball Savant

His launch angle of 6.9 and 7.5 degrees in April and May respectively was in-line with his average launch angle 7.8 between 2015 and 2018, when Statcast started tracking that data.

However, in the following months, Castro never boasted a launch angle below 11 degrees.

With that extra launch angle, Castro recorded more of what Statcast calls Barrels. These are instances where a ball in play has an expected batting average of at least .500 and an expected slugging percentage of at least 1.000 based on exit velocity and launch angle.

Below, you can see the big jump in the percentage of balls that were deemed barrels that Castro hit late in the season in August and September...

Courtesy of Baseball Savant

Looking at some of the underlying stats, the jury is still out as to whether Castro can sustain the production he displayed in the second half of last season as we move into 2020.

Following the All-Star Game, Castro posted a .370 wOBA, according to Statcast. Meanwhile, his xwOBA, a figure that tries to calculate what a player’s wOBA would be based on exit velocity and launch angle, was a little lower than that at .344, also according to Statcast.

There’s every chance that this could just have been a hot streak, something Castro has been known to have occasionally in his career. It’s also possible that with a bit more film on his new swing, pitchers may adjust back and exploit holes in his new mechanics.

If the Nationals truly are going to try and replace Anthony Rendon’s production with a collective effort, they’re going to need several players to step up and perform.

Castro will have to be one of those players. Though he’s been basically a league-average bat in his career, if he can replicate his second-half showing from 2019, he has a chance to do his part in replacing the production of the team’s former third baseman.