Rosario had his challenges, but he also had his conquests. His defense is a work in progress, but the offense already shows impact potential, although it, too, is still developing.
"He caught one of the most challenging pitching staffs in history," said Rockies general manager Dan O'Dowd. "There is certainly room for growth, but somebody needs to cut the kid a break."
Rosario, who jumped from Double-A to the big leagues out of Spring Training, was supposed to make a slow transition to full-time duty. The plan was to have him share the catching chores with Ramon Hernandez, who was to serve as a veteran tutor.
So much for those plans. With Hernandez battling injuries, Rosario's workload increased. He wound up starting 100 games behind the plate. It wasn't always pretty, but it was promising.
Yes, he led the Majors with 21 passed balls and 13 errors, and he was behind the plate for 63 wild pitches -- more than the total for 14 other NL pitching staffs. But Rockies pitchers threw 31 wild pitches when someone other than Rosario was behind the plate, too. And the staff ERA with Rosario was 4.98, compared to 5.59 with Hernandez, Wil Nieves and Jordan Pacheco catching.
Rosario did, however, throw out 32 percent of runners attempting to steal, compared to 18.8 percent for the three other Rockies catchers.
"He had to handle a lot of young pitchers and a staff that struggled as a whole," said O'Dowd. "He's still a pup. Because of his desire to get better and his passion for the game, he has a chance to be a good one."
Rosario did spend the final weeks of the regular season working with Rockies catching guru Jerry Weinstein on a winter routine, which included catching for Aguilas in his native Dominican Republic.
"I am going to be a good catcher," Rosario said. "I promise. I am not afraid of hard work."
Because he was signed at the age of 17, it is easy to forget he is only 23. Had Rosario played in college, he would have just finished his second Minor League season. Instead, he spent five years in the Minor Leagues in the United States, but his playing time was limited -- initially because of youth and then because of injuries.
Rosario arrived in the big leagues with only 284 games caught on his resume.
"What he shows you is a young man with a great attitude and a very realistic chance to be a catcher with offensive impact," said O'Dowd.
Check out the final offensive line for the rookie season: He hit .270, and despite only 398 at-bats he had 28 home runs and 71 RBIs. He tied with Washington center fielder Bryce Harper for the sixth-best average among NL rookies with 400 plate appearances, and Rosario led NL rookies in both home runs and RBIs.
He hit six more homers than Harper, who was No. 2, and drove in four more runs than Todd Frazier of Cincinnati. Harper was fourth among NL rookies with 59 RBIs, also trailing Yonder Alonzo, who drove in 62 runs for San Diego.
Rosario hit 27 home runs while catching, the third-highest total in Major League history for a rookie. Mike Piazza hit 35 as a catcher for the Dodgers in 1993, and Matt Nokes had 28 while behind the plate for Detroit in 1987.
And Rosario got better as this season went on. After hitting .247 with 14 home runs and a .297 on-base percentage before the All-Star break, he hit .291 with 14 home runs and a .342 on-base percentage after the break, making a major adjustment to breaking balls, which pitchers used to exploit his aggressiveness in the first half of the season.
He was under the radar most of the season.
But the more Rosario played, the more attention he attracted.