Aaron Miles, who has been bothered by a sore right shoulder since Spring Training, was placed on the 15-day disabled list as well. Miles received a cortisone shot on Tuesday night and was to go to the team's Mesa, Ariz., facility to rehab, then join Triple-A Iowa for some games before he is activated.
Miles was batting .204 with six doubles and four RBIs in 37 games. Blanco, who was hitting .314 at Iowa, started at second base on Wednesday in the Cubs' series finale against Pittsburgh, but will primarily be a backup at shortstop.
Fox, 26, was leading all Minor League players with a .423 batting average, 17 home runs and 50 RBIs in 40 games. The only problem has been finding a position for him to play, and he will be initially used as a bat off the bench.
"He gives us a good bat coming off the bench, a power bat," Cubs manager Lou Piniella said. "We haven't had that. This gives us more firepower."
"My kids haven't put up those numbers on the video game," Cubs player development director Oneri Fleita said. "Those are numbers you dream of. For some guys, that's a season. He did what you're supposed to do -- he's down there, grinding it out, waiting for an opportunity."
Fox, 26, has played first, left field, right field, third base and even caught two games.
"He's got about eight different gloves," Fleita said. "Put me in coach, he'll drive the bus. He'll give it his best effort any opportunity he gets."
The Cubs have been searching for someone to fill in at third while Aramis Ramirez is sidelined because of a dislocated shoulder. Ramirez isn't expected back until the first week of July. He was hitting .364 with four home runs and 16 RBIs before he was injured on May 8. The fill-in third basemen have combined to hit .191 with four homers and 16 RBIs.
Could Fox handle third?
"There's a difference between what I think and they think," Fox said. "I felt comfortable there. It's just a different spot. It's like in the last three years, I've learned four different positions. Would I make mistakes there? Yes, I would because I haven't gotten many innings. I feel with the time and the work, I can play anywhere."
He's shown he can hit.
"It was a combination of being more consistent and taking it one day at a time," Fox said. "It makes it a lot easier when you're not concentrating on the big picture, but only concentrating on one day at a time, winning that game, doing what it takes to win that game."
Cotts was 0-2 with a 7.36 ERA in 19 relief appearances this year. Pitching coach Larry Rothschild has been working with the lefty on changing his grip on his breaking pitches in an attempt to be more productive. The only southpaw in the Cubs 'pen, Cotts wasn't consistent. Left-handed hitters were batting .318 against him.
"He's got a good arm," Piniella said. "There's no reason he shouldn't be successful at the big league level. It's a little befuddling."
Cotts spent most of last season with the big league team, but also had a stint at Iowa to get back on track.
"It's one of those things where you get in a rut and sometimes it's hard to get out of it," Cubs general manager Jim Hendry said. "Hopefully, he'll go down there and clear his head. It certainly shouldn't be his last chance at the big leagues. He went down there and got it together. Hopefully, he'll do it again."
Cotts recognizes he needs to be more consistent.
"You've got to produce up here, and I didn't," he said. "Command of the fastball, I had trouble throwing strikes early in the year. I'm throwing strikes now, but you need to put it in the corner or down at the knees. It was getting better, but it happens."
Was it frustrating not being able to get lefties out?
"It's frustrating not getting anybody out, to be honest," Cotts said. "You've got a job to do and you need to be able to do that."
Waddell impressed the Cubs in Spring Training. This is his first Major League callup after eight years in the Minor Leagues. At Iowa, he was 0-1 with a 5.40 ERA in 18 appearances, giving up runs in four outings, including five in one-third of an inning May 12 against Colorado Springs.
"They said I opened up some eyes and keep doing what you're doing and we'll see you up here," Waddell said. "Turns out they were right."
Blanco gives the Cubs a better backup option at shortstop than Scales, who was hitting .257 in 14 games for the team in his first callup after 10 years in the Minors.
"I felt like I did OK," Scales said. "They told me as much in the meeting. I'd like to think I'll get the opportunity to come back and help this team win."
Carrie Muskat is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.