Oberg, 25, who had 15 saves at Double-A Tulsa last season but made just 27 appearances because of an injury to his right shoulder, has a 9.00 ERA in five Cactus League outings, including a scoreless one-third of an inning on Thursday night against the Rangers. But all five runs he's allowed came in one game, against the Angels. Three of those came on one Mike Trout swing. He gave up five hits in that game against the Angels but just one other hit, and has six strikeouts against one walk.
Oberg underwent a cleanup surgery on his rotator cuff and labrum last August, but doctors did not have to stitch the area, so rehab was quick.
"My goal coming into Spring Training was to make sure I stayed healthy, and the goal right now is to make good, competitive pitches," Oberg said. "I have the fastball and curveball, and I'm starting to get comfortable with those in any count. I have worked on the slider, still trying to get a feel for that."
The time in Rockies camp has allowed Oberg, a 15th-round pick out of UConn in 2012, to listen to veterans LaTroy Hawkins and Adam Ottavino for pointers on the slider. Another valuable resource has been bullpen coach Darren Holmes, who proved during his career that a pitcher can use a curve at Coors Field and succeed.
Roberts, 27, went 9-2 with a 2.30 ERA at Double-A Tulsa last season and had sub-2.00 ERAs at the short season, low-A and high-A levels. A 25th-round choice out of Middle Tennessee State in 2010, he has hit every step of the ladder but at least is close enough to the top to see it.
Roberts has yielded just one run in seven appearances in six innings.
"There are fewer and fewer lockers, and it's over a week away, so you see that, but you can't get caught up in that stuff," Roberts said. "You've got to stay in the process. They're going to need more than the 12 or 13 guys they take out of camp."
Thomas Harding is a reporter for MLB.com. Read his blog, Hardball in the Rockies, follow him on Twitter @harding_at_mlb, and like his Facebook page, Thomas Harding and Friends at www.Rockies.com. This story was not subject to the approval of Major League Baseball or its clubs.