Nippert has a good fastball and a big overhand curve. He was able to have success with those two pitches coming up through the Arizona system as a starter, but he struggled to come up with a consistent third pitch he could use on days he wasn't able to throw his curve for a strike.
That was one of the reasons the team thought he would be best suited to the bullpen and moved him there last year. This offseason he has worked on improving the changeup, but also continued to develop a slider.
It's a pitch he began throwing during side sessions last year and broke it out against hitters for the first time when he tossed live batting practice between the National League Division and Championship Series.
"I was throwing it wrong in the past," Nippert said of his experience throwing a slider before last year. "I was trying to get around it rather than staying on top. I guess it was just inexperience on my part. The curve is such a feel pitch, so if I don't have a feel for it, now I can go to the slider."
Though it was a mechanical adjustment that led to his breakthrough with the slider, getting it to the next level will involve something different.
"It's really all in my head now," he said. "I just have to trust in my ability to throw it and have confidence in it."
Options: Several D-backs players are out of Minor League options, which means if the club were to try to option them, they would have to clear waivers first before re-joining the club's Minor League ranks.
Pitchers Edgar Gonzalez, Nippert and Brandon Medders, along with outfielder Jeff Salazar and infielder Augie Ojeda, are among the more noteworthy D-backs who are out of options.
The player who appears most at risk right now is Medders, because as things stand, it doesn't look like there will be a spot for him in the bullpen, provided Doug Slaten is recovered enough from microfracture surgery on his right knee to be ready for Opening Day. Slaten would join Gonzalez, Nippert, Cruz, Chad Qualls, Tony Pena and Brandon Lyon in the bullpen.
"We do like the group we have, and barring injury and so forth, it's a good group," D-backs manager Bob Melvin said of his bullpen. "But you also want to leave a light at the end of the tunnel for everybody else, because they're here to be seen, too, and they're here for a reason. In baseball, there is always competition."
If a player is claimed on waivers, the team that claims him must keep him on its 25-man roster. If the team that claims him wishes to send him to the Minors, he once again must be placed on waivers.
Welcome to Tucson: Outfielder Eric Byrnes joined his teammates in camp on Monday.
Byrnes, who like many of the team's position players is in camp well before Wednesday's reporting date, was pulled over by Tucson police on his way to the ballpark because his license plates had expired. He'll spend Tuesday morning trying to get it straightened out at the Department of Motor Vehicles.
"It feels good to be back and see everybody," Byrnes said. "I'm real excited about the year. We've got a good group of guys, a real good group of guys."
Decision time: D-backs general manager Josh Byrnes said the team will decide "in the next day or so" whether or not to sign free agent Trot Nixon, who worked out for the team Sunday.
"The ball was still jumping off his bat," Melvin said.
Golden: The fact that Wes Roemer, who was one of Arizona's two sandwich picks in the 2007 First-Year Player Draft, finished first in running drills by the pitchers prompted one of the first clubhouse pranks of the year Monday.
A player, or players, apparently took Roemer's spikes and tennis shoes from his locker early in the day, and when they were eventually returned, they were spray painted gold. It was a nod to former United States Olympic sprinter Michael Johnson, who wore gold shoes while winning five gold medals in the 1992, 1996 and 2000 Olympics.
"I thought that was good, and he took it very well," Melvin said of the prank. "You see quite a bit of that in camp, and I think that's good for morale -- it keeps things light. Where he's going to find his next pair of shoes, I'm not sure, but I'm sure they'll take care of him down the line."
Game time: The D-backs likely will play an intrasquad game on Feb. 27, one day before they open Cactus League competition against the Rockies at Tucson Electric Park.
Tuesday: The team once again will work out over at the Kino Sports Complex beginning around 9:30 a.m. MST on Tuesday. The mounds the pitchers throw off are in an area the public is not allowed into, but fans can watch the pitchers' fielding practice on the main diamonds.
Steve Gilbert is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.