"I have no words to describe it -- he's just been phenomenal," Montero said. "He's been outstanding at everything -- hitting, catching. His hitting has been unbelievable. Since I went down, he's just taken over and done a great job."
Nieves hit .306 for the D-backs last season after being claimed him off waivers from the Rockies in early August. He was arbitration-eligible this past winter, and the D-backs non-tendered him because they didn't want to pay him the $1 million-plus that he figured to get through that process.
"We kind of knew what we wanted to pay for that backup position, knowing that more than likely if Miggy stayed healthy that person probably would only catch 20-25 games," D-backs general manager Kevin Towers said.
Finding a backup for Montero, though, proved to be harder than the D-backs thought.
After all, Montero led all Major League catchers in innings caught in 2011-12, and taking days off was just not a regular occurrence for him. That turned off some free-agent backups who were looking to get more playing time.
Nieves finally re-signed with the D-backs in early December for $800,000, which would only become guaranteed if he made the Opening Day roster.
As camp opened, the D-backs signed veteran Rod Barajas to a Minor League deal to compete with Nieves for the backup role, and the two battled to a near draw before the D-backs decided to go with Nieves. The decision was made in large part because the club felt in the unlikely event that Montero went down for an extended period of time, Nieves would be able to physically handle an everyday role better than Barajas.
"Even though Barajas had maybe a little better spring, Nieves was the right choice," Towers said.
Over the last couple of years, Nieves has found peace -- and success -- in accepting his role as a backup. At age 35, he is mentally stronger than he was as a young player.
"I think I'm a better player now than I was before, especially as a backup," Nieves said. "I understand my role and I don't try to do too much, I don't try to prove to everybody that I'm a regular catcher. I believe I can be an everyday catcher, but I don't need to prove it to anyone. So now I don't worry about the results, I just worry about having good at-bats."
It has been a long journey for Nieves, who was initially signed by the Padres as a non-drafted free agent in 1996. Since making his Padres debut in 2002, he has bounced up and down between the big leagues and Triple-A while trying to find his place in the game.
At times, there was some bitterness when Nieves thought some catchers got promoted to the big leagues over him, and at times he felt he may have gotten shortchanged contract wise.
In 2011, the Brewers dealt Nieves to the Braves for $1 in July after Atlanta's starting catcher, Brian McCann, went down with an injury.
"Maybe back then if I had it, I wouldn't have appreciated it or I would have gone down another road," Nieves said of a starting role or bigger salary. "Now I have a wife and a daughter, a great family, and I appreciate everything. Now I'm more mature, and hopefully, finally something good will come to my career, contract-wise. Now I'm more mature and am able to receive something good."
Montero and Nieves talk all the time about game plans and how to handle the pitching staff, so much so that the D-backs pitchers say there has been a seamless transition when it comes to calling games.
"When we go out there, we trust what he's putting down and it makes things a lot easier, because you're not having to shake him off," Arizona ace Patrick Corbin said. "We can just commit to our pitches."
It's hard to pinpoint exactly why Nieves has had such a breakout year at the plate. His batting average on balls in play (.411) indicates there's probably been some good fortune at work, but Nieves also credits his improved routine during batting practice and in the cage.
Whereas he once used batting practice to see how far he could hit the ball, he now focuses on his mechanics at the plate.
"You create good habits there, and then when you go into the game you don't have to think about mechanics," Nieves said. "So if you practice the right way, muscle memory will take over and you'll do it in the game without thinking about it."