Rusney Castillo adjusts on the fly amidst torrid Winter Ball stint

There was a lot to like about Rusney Castillo in his first month in the major leagues. In his short stint with the Red Sox during the month of September, Castillo displayed the tool set that netted him a seven-year, $72.5 million contract despite the fact that he had not seen a pitch, let alone played, in a major or minor league inning. The 27-year-old displayed a whip-quick bat among other tools en route to a .333/.400/.528 line with two home runs and three stolen bases in 40 plate appearances.

Even the best tools could use refinement, though, and Castillo, who had not played a competitive baseball game in two years before coming to Boston, required just a little more time to sharpen up on the baseball field. After a minor thumb injury set Castillo back in the Arizona Fall League, general manager Ben Cherington made the decision to send the outfielder to former Red Sox infielder Alex Cora, who manages and serves as general manager for Criollos de Caguas in El Liga de Beisbol Profesional Roberto Clemente, in the Puerto Rican winter league.

Cora, who played for Boston from 2005 through 2008, had texted Cherington offering Caguas as a place for Castillo to get more playing time, similar to how Dodgers outfielder Yasiel Puig played on the island in 2012 in preparation for his first season in the United States.

Castillo, who hit .405 with a home run, two stolen bases, two walks and four strikeouts in 37 at-bats for Caguas, certainly left an impression on Cora.

"He was more polished than what people thought or let me know about him. He's a complete player," Cora said via phone on Thursday. "He's got a pretty good idea about the game. His baseball IQ is solid. He understands it and we were very impressed with the way that he plays the game, he's been taught the game. He thinks the game. He's a good player."

"A lot of people told me, not the organization, but other people told me that his instincts weren't that good. They thought because he hadn't played for a long period of time that he was a little bit off as far as that. For me, it didn't look that way. He paid attention to the game, took advantage of certain situations and, offensively, he has a pretty good idea of what he wants to do."

What impressed Cora the most was how Castillo used the whole field, not during batting practice, but during games.

"In batting practice, he's driving the ball to right center, right center, right center," Cora said. "During games, I really loved the way that he went back to the middle and went the other way. That's what he tried to do the whole time and he was very successful."

Defensively, Castillo caught Cora's eye as well.

"He gets good jumps. Great jumps, actually," Cora said. "In center field, he covers a lot of ground and he gets to the ball very quick without too much effort, which is the sign of a good center fielder. He didn't need to leave his feet to get to any balls. He'll get to the ball under control with crisp routes."

So while Castillo certainly has a lot of things going his way, there are areas that he continues to focus on for improvement. In Puerto Rico, Castillo fixated one area on his batting stance.

The Leg Kick

During the last month of the season Castillo began to develop a leg kick in his batting stance. The difference in his mechanics became more and more noticeable as September came to an end. Check out Castillo's swing in his major league debut on September 17.

And here is Castillo's swing ten days later on September 27.

Castillo's leg kick became significantly more pronounced over the course of the month. It's an adjustment, that Cora says, will be beneficial for Castillo moving forward.

"Now, he stays squared the whole time," Cora said. "He's in a good position to attack any pitch. He was coming up through the strike zone. Now, his bat head stays through it and he can do whatever he wants with any pitch."

Cora said that the adjustment gives Castillo more bat control and allows him to control the strike zone. Before he added the leg kick, Castillo's load, which is where a hitter generates momentum for power in a swing, would solely consist of a shoulder turn. There are issues inherent with such an approach.

"When you turn that left shoulder and he's right-handed, the only way you can get out of that is by pulling off [to the left]," Cora said. "When you pull off, your head pulls off and that pitch outside that he can do damage with, it goes farther away from him and he's going to start to hit things off the end of the bat. Even the pitch inside, he'll be rolling over instead of hitting it by staying square and using his hands to stay inside the ball and he can drive the ball to right center."

A closer look at Castillo's load illustrates the precise problem Cora speaks of. Watch Castillo's shoulder in this at-bat from his major league debut....

... versus his shoulder in his at-bat ten days later against the Yankees.

With the addition of his leg kick, Castillo is able to keep his body more squared towards the pitcher, allowing him to keep his momentum moving forward towards the mound versus towards the Red Sox dugout. This slight adjustment, if Castillo can make it stick, will allow him to benefit in multiple facets of his offensive game. Cora saw this come into play firsthand in Puerto Rico.

"It was very interesting, a lot of guys, sometimes, it looked like [Castillo] was going to get beat, but he's very disciplined at what to swing at on the inside part of the plate," Cora said. "If you couldn't throw strikes in there, a lot of those guys get in trouble because then he just looks at one spot, one spot only and he'll drive the ball to right-center.

"It's just a matter of being disciplined with it. A lot of Cubans [wrap their shoulder in their swing] and they are so violent with their swings, but that's not the case with him. His swing is under control compared to Yasiel Puig and Yoenis Cespedes. His preparation and work ethic are great. He uses the tee to work on his swing and you can tell. You could say that his swing is more "Americanized" compared to the other guys."

The Outlook for 2015

As an older rookie, Castillo finds himself in a unique situation. Cora saw Castillo's willingness to teach and learn the game front and center during the outfielder's stint in Puerto Rico.

"I love the fact that he's a 27-year-old rookie so he's mature," Cora said. "He's a baseball rat. He loves playing baseball. We talk about playing baseball in PlayStation 4 at night. He's a very caring person and he got along with everybody and I think he has a lot of fans from his ex-teammates down here in Caguas. We're cheering for him and hoping for the best because he was great for us."

Personality wise, Cora said Castillo's quiet, but caring temperament stood out to everyone around the team.

"Family oriented. His wife was here the whole time and we had time to spend together and show him the island and hang out with them and they care about people," Cora said. "When you gain his trust, he was great with us. He would text us and see how we're doing and all of that stuff. He's a good guy. He's gonna be in a good situation there with, not only the Latino players, but with the other guys that play there. I know how caring they are about their families and he'll fit right in."

Cora was hesitant to project 2015 numbers for Castillo, but the 39-year-old skipper did not hold back praise for the outfielder's talents.

"He's going to contribute. In the situation that he's in, the spotlight will be on him because he's making a lot of money without throwing a ball in the big leagues, but if they hit him at the top of the lineup or the bottom, he's going to succeed," Cora said. "If he keeps his approach, hitting to right-center, he's going to take advantage of a lot of hanging breaking balls and hit it off that wall. He'll be a good player."