NEW YORK -- The friendship between Yairo Munoz and Jose Martinez was struck on one of Munoz's first days at Cardinals camp. The 23-year-old was so green, some of his gear still sat in an Oakland A's equipment bag. Its gold-and-pine design clashed noticeably against his new clubhouse's red-and-white décor.
The first conversations came, naturally, in the batting cage. In an environment full of new sights and sounds, Munoz gravitated towards the baseballs Martinez sent flying from his bat. How they sizzled, and how far they travelled through the air. In his native Spanish, Munoz asked Martinez how he could get them to do the same off his.
"I didn't know him before," Munoz said through interpreter/first-base coach Oliver Marmol. "I was watching Jose hit and realized he got a lot more backspin on his ball than when I hit it. I asked him a couple of questions and Martinez said, 'Tag along with me.'"
What resulted was the type of swing change most hitters take longer to complete, and it translated into production the Cardinals could not ignore. The club adores Munoz's defensive versatility, and more than anything, his ability to play all over the diamond was ultimately what landed the rookie on St. Louis' Opening Day roster. But it was his swing -- just tweaked -- that eventually made him a revelation of the spring for the Cards.
"It's really hard to show up to Spring Training and just start raking," Martinez said. "He did a great job proving he belongs here."

At Martinez's advice, Munoz adjusted his bat path in the way many have over the past few years -- by flattening his swing in an attempt to "get behind the ball" more. The goal was to create line drives with "more carry," Munoz said, to improve on the doubles power he showed as a Minor Leaguer.
"Wait longer, then push through the ball using your bottom hand," Martinez said. "To me, ground balls are not allowed."
It was the same idea Martinez brought to camp last year, when he slugged his way onto the roster with his own sensational spring. This year, he acted as a mentor to Munoz, providing tips and translating between him and coaches John Mabry and Bill Mueller. Munoz hit .323/.364/.516 with 20 hits in Grapefruit League play, one more than Martinez collected the spring before.
"The student surpassed the teacher," Martinez said. "The alumnus surpassed the master."
The Cardinals' plans were twofold for the deal that yielded them Munoz and second-base prospect Max Schrock from Oakland on Dec. 14. They were looking to both unclutter their outfield alignment and give Stephen Piscotty a chance to play closer to his ailing mother. But they also sought to add infield depth to a Minor League system they felt lacked it. Munoz was supposed to provide insurance in that regard.
"Coming into this spring, he wasn't the favorite for a roster spot," general manager Michael Girsch said. "But you watch him take 60 at-bats, and it grows on you."