"[Christian] was a guy that everybody said was a leadoff-type guy, and he very well could be," Mattingly said. "They're guys that can really hit. Guys who hit both sides -- hits righties, hits lefties. Hits good pitching."
In Castro's first year with the Marlins, Mattingly plans on using him in the spot generally reserved for the club's top all-around hitter. The 27-year-old isn't necessarily a home-run threat, but he's had a track record of getting key hits and getting on base. The hope is Castro will be on base often for Justin Bour, who already has been tabbed to bat fourth.
"I've talked to [Castro] about it, hitting in the three-spot," Mattingly said. "He's a guy who can get on base for J.B., but also can drive in a run. Hopefully those guys on top are on base, and he just gets his hits."
The Marlins acquired Castro from the Yankees in the Giancarlo Stanton deal. A four-time All-Star, Castro has a proven track record, both at the top and in the middle of the order.
"I've been hitting everywhere in the lineup," Castro said. "I don't try to put pressure on myself, and I keep the same approach. I want to be the same hitter, be the same person. Just be the same. I don't try to put anything else in my mind. Go play and have fun."
Castro is no stranger to batting third, doing so 135 times in his career and posting a slash line of .264/.291/.400 with 11 home runs and 61 RBIs.
"He can hit," Mattingly said. "So I'm not asking him to go in there and hit homers or anything else. But get his hits, and he will drive in some runs."
With the Yankees last season, Castro batted third in nine games, and in 39 at-bats he hit .405/.436/.703 with three home runs and seven RBIs.
"I like hitting there," Castro said. "We're going to get on base. We've got guys here who can get on base. You just don't try to get too quick [with your approach]. Just get a good at-bat and use the whole field."
A pure hitter since he broke in as a 20-year-old with the Cubs in 2010, Castro has batted up and down the order. But a majority of his plate appearances have been in spots one through six, with more than 100 starts in each of those slots.
Not a huge power threat, Castro enters the season with 99 career home runs. He also has had more games in the cleanup spot (175) than hitting third. With New York in 2017, Castro had 159 plate appearances batting fourth, and he posted strong numbers -- .318/.352/.426 with two home runs and 18 RBIs.
The veteran infielder also has shown he can impact the baseball. According to Statcast™, his average exit velocity on balls put in play was 87.4 mph, which was fourth on the Yankees among players with at least 150 attempts. Aaron Judge (94.5 mph), Gary Sanchez (90.9) and Matt Holliday (89.6) were the only players higher.
In his final season with the Yankees, Castro spent his most time batting fifth, which he did in 52 games. He had 216 plate appearances there with a slash of .236/.278/.399 to go with nine homers and 31 RBIs.
"Last year, I started off hitting sixth," Castro said. "I started hitting pretty good, and they put me in the fourth spot. I hit there for like two months."