For now, though, the 23-year-old is more like a co-pilot, with the veteran Ramon Hernandez doing the majority of the steering. But after Rosario performed well in camp, and followed it with impressive work in his first start of the season, the Rockies are expecting him to soar.
On Sunday against the Astros, Rosario knocked a two-run homer off Bud Norris to give his team a two-run lead. He also threw out Jordan Schafer attempting to steal to end the first inning. This came on the heels of a Spring Training in which Rosario hit .418 with four home runs, eight doubles and 12 RBIs to earn his place on the team.
Rosario also showed dramatic progress defensively, an area of concern during a 16-game Major League trial last year after he was called up from Double-A Tulsa. In a game late in the Cactus League schedule, Rosario was timed at 1.75 seconds from catch to tag when he erased Texas' Mitch Moreland on a steal attempt at second.
In a nod to Rosario's rapid development, manager Jim Tracy didn't hesitate to sub him for Hernandez in the eighth inning of Friday night's 5-3 season-opening victory.
"Wilin Rosario on both sides of the ball has been fun to watch," Tracy said.
And there's more to Rosario behind the plate than shiny new gear.
Rosario took Hernandez's advice to relax his muscular 5-foot-11, 215-pound frame, which has made him more nimble and better able to handle pitches that come in tight to the batter. Those pitches were a problem last year, when Rosario was charged with three passed balls and was behind the plate for 13 wild pitches.
Rosario's biggest forward step, however, can be seen before the ball is even thrown.
Because he skipped Triple-A, Rosario did not get experience running a game against opponents who had built a large number of plate appearances and had established tendencies on the bases. All that comes into play when a team sets its defense against a batter or when a running game needs to be controlled. That is done by the catcher, often by relaying a signal from the bench.
During his callup last year, it was all Rosario could do to learn the signs. He was trying to interpret what the signs meant as he was relaying them, which is not the way to provide the authoritative leadership the position demands.
"Sometimes he'd give me that stare like, 'Uh ... oh, yeah!' But not anymore," said bench coach Tom Runnells, who said that the Rockies were more patient with Rosario's mistakes last year but have raised the standard for execution this season. "The continuity and fluidity of the game is really nice. Wilin has spent a lot of time making sure he knows the signs, and he understands the situations. He's at much more ease."
Rosario's ability to call pitches -- solely his department, based on game situation and a pitcher's effectiveness on a given day -- also took a leap, thanks to an odd coupling the Rockies forged this spring.
On one side of the clubhouse, Rosario listened to music or played games on a smart phone. Across the room, 49-year-old pitcher Jamie Moyer, black-rimmed reading glasses perched low on his nose, propped up his feet and read a newspaper. Rosario had difficulty bridging this generation gap.
Rosario was asked to catch Moyer's start against D-backs Minor Leaguers. It didn't go well for Moyer, and Rosario was too awed to help.
"II was like, 'Oh my gosh. I'm going to catch that guy?'" Rosario said. "I didn't want to say, 'Stay behind the ball,' even though I saw that."
Moyer recalled his days with the Phillies, when young catcher Carlos Ruiz hesitated to take charge. He encouraged Rosario to bring him ideas, and Rosario ended up catching the rest of Moyer's Cactus League starts.
"I don't feel I should be intimidating anyone or [that] he should be afraid," Moyer said. "This is a game that you have to rely on many people to play. You try to constantly tell him, 'You've got to stay with who you are, and your instincts will get you through this. Your instincts will allow you to learn. Your instincts will allow you to get better.' And he'll gain confidence."
Rosario has also made dramatic strides offensively. Last year, opponents immediately saw that he'd chase low-and-outside pitches, and he ended up hitting .204 with 20 strikeouts in 54 at-bats.
Rosario went home to the Dominican Republic for winter ball, started hot, then fell into the same habits as veteran pitchers took advantage of his aggressiveness. Before camp began, the Rockies signed veteran backup Wil Nieves in case Rosario needed time to slow the game. Nieves performed well defensively and hit .409, but Rosario grew up in a hurry.
The Rockies intend to rest Hernandez, who turns 36 in May, often, which means that Rosario will play semi-regularly, at least for now.
"He will be the catcher for this organization for a long time," Hernandez said. "He has the tools. Everything now is how bad he wants it. It's all about how much mentally you prove that you want to stay for a long time."
Rosario insists that all will be safe when his turn comes.
"In the past, I was in a little bit of trouble," Rosario said. "I didn't know if I can capture everything. But now I feel comfortable, slowed down. You can see how I look."