But he also led the Majors in passed balls (21) and was the primary catcher for a Rockies pitching staff that led the Majors with a whopping 94 wild pitches -- 19 more than the team that finished second, the Astros. Some of those wild pitches were preventable.
After returning to his native Dominican Republic, Rosario has spent part of this offseason working on fundamentals at the Rockies' complex in Boca Chica. In late November he joined the Dominican Winter League's Aguilas -- managed by former All-Star catcher Tony Pena and with Alberto Castillo, who was a strong defensive catcher during his 12-year career in the Majors, on the coaching staff.
However, Rosario hasn't played since Dec. 5, when he was hit on the left forearm by a pitch. Listindiario.com in the Dominican Republic reported Tuesday that Rosario is expected to return to action this weekend. The Rockies, who asked the Aguilas to give Rosario every third game off to give him a good mix of game and practice work, have said they want Rosario to end his winter participation around the holidays.
The practice time is crucial, the Rockies believe.
Rosario showed signs of a power bat during a brief Major League callup in 2011, but he hadn't played beyond Double-A previously. As expected, his defense was rough. Pitches inside to hitters were especially troublesome.
After that season, the Rockies signed veteran Ramon Hernandez to do the bulk of the catching in 2012 and had journeyman Wil Nieves in the fold so Rosario could begin the year at Triple-A Colorado Springs.
However, Rosario dazzled then-Rockies manager Jim Tracy and the front office during Spring Training, hitting .418 with four home runs and 12 RBIs in 23 Cactus League games. The club kept him as Hernandez's backup, believing he could play enough to stay sharp and use the days he wasn't playing to continue working on fundamentals.
The plan went awry on May 25 when Hernandez went to the disabled list with a left hand injury and missed 42 games. Hernandez continued to battle health issues until undergoing season-ending surgery in September to repair a torn left hamstring.
Catching in 85 of the Rockies' final 119 games allowed Rosario's offense to shine, but he also had to fight the glare of the spotlight drawn to his defense.
Many issues arose. Rosario was stiff, and pitches he blocked ricocheted away. Teams noticed that he would narrow his feet when setting up for a fastball and widen dramatically for a breaking pitch. Balls that bounced between his feet escaped to the backstop -- sometimes because he'd stab at them rather than turn over his glove, sometimes because he was late sinking his bare hand and his legs to stop the ball. It all led to his worst performance: Sept. 9 in Philadelphia, when Rosario lost pitches in the creeping shadows during the first game of a doubleheader and was charged with four passed balls.
Rosario would pick an area of concern to work on before the game with Rockies catching coach Jerry Weinstein. But sometimes the emphasis on one area left him overly conscious of it at game time, and he was slow to react when other situations would arise.
"You can get better during the season; You just can't do it as fast," said Weinstein, who visited Rosario in the Dominican Republic a couple of weeks ago and reported improvements. "It's like you can get stronger during the season but you can't get as strong as you can when all of your focus is on technique."
It was a tough set of events for young but proud player.
"Sometimes when I hear people talking about my defense, I feel bad about myself because a lot of things happened during the year," he said. "But I know that next year things are going to be different with my defense. I know how to work. I know what I need. I know now how I can control it. I am motivated."
To his credit, Rosario never lost his aggressiveness. For all the struggles catching the ball, he was a threat against the running game. He erased 31.9 percent of would-be base-stealers to rank fifth among NL catchers.
Even with the bat, he could look bad on a breaking pitch but finish the at-bat by driving the ball. He finished with a .270 batting average and .312 on-base percentage -- not bad considering that with Troy Tulowitzki out most of the season with a groin injury and Carlos Gonzalez rarely seeing fastballs in the strike zone, Rosario was the Rockies' best hope for power and teams tried to attack his inexperience.
New manager Walt Weiss believes Rosario's irrepressible spirit will make him a star.
"I don't have a lot of concerns about Rosario, even though he struggled some last year as a young catcher," Weiss said. "I truly believe this guy is going to be a star, and not only because he hits home runs but because he's got the ability to shut down the running game, too."
On a few occasions, Tracy played Rosario at third base and first base. The results weren't pretty.
That's fine with Rosario, who believes he will personify beauty behind the plate.
"A lot of people make a lot of it, but if things don't happen, you don't know what you have to work on," Rosario said. "You'll see what happens."