Nix hit .111 (5-for-45) with one double and two RBIs in 16 games, including 15 starts, after winning the job out of Spring Training. He struck out 12 times. The Rockies purchased the contract of right-hander Jose Capellan from Triple-A Colorado Springs to take Nix's place.
"One of the things that we shared with [Nix] today from the coaching standpoint was this was his first look," Rockies manager Clint Hurdle said. "This needs to be treated as an experience. Most of the guys we have brought up have had a September callup involved or another opportunity to cut their teeth. This wasn't the case with him."
The Rockies officially have 10 days to determine whether to release Nix, trade him or assign him to the Minors. The club plans to place him on waivers and assign him to Colorado Springs when he clears. That's likely, since a team that would claim Nix would have to put him in the Majors, or go through the same process to get him to the Minors.
Nix, 25, was the Rockies' top Draft choice, 44th overall, in 2001, but he had offensive difficulty in 2005 and 2006. He had a strong 2007 at Colorado Springs, but there was no room in the Majors for him during the Rockies' late-season playoff run. As he battled to make the Majors, his Minor League options were exhausted, which is why the Rockies have to expose him to other clubs via waivers.
Nix earned most outstanding player honors for Team USA in the International Baseball Federation World Cup. He came with raves from Rockies Minor League personnel. But his struggles allowed Clint Barmes (.321 going into Saturday) to grab the second-base job. In a last-chance start on Friday, Nix went 0-for-6 with two strikeouts.
"I know I can handle anything and deal with anything," Nix said. "I've been through a lot. This is just another little adversity that I'll face, and I'll handle this one, too. This game isn't easy for anyone. I know I'm not the first person to be in this situation.
"I was comfortable playing here. It's just a matter of locking in on your approach. There's a lot of new information you get when you're here about opposing pitchers and different things. Then it's a matter of keeping it as simple as possible, and I was never exactly able to settle into anything."
The demotion of Nix and addition of Capellan, 27, who went 2-0 with a 3.94 ERA in three starts at Colorado Springs, leaves the Rockies with one backup infielder. It was Jeff Baker on Saturday night. Hurdle said he did not plan to go with an extra pitcher indefinitely, but the bullpen was taxed Friday because starter Ubaldo Jimenez lasted just 2 1/3 innings in a 13-inning loss to the Dodgers.
Thomas Harding is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.