Wood hasn't pitched since April 13, and he received a cortisone shot in his shoulder on Wednesday. He was slated to be the Cubs' primary setup man to closer Carlos Marmol this season but had thrown just 2 1/3 innings over four appearances and has an 11.57 ERA.
Cubs manager Dale Sveum says the injections seem to have helped, but the club is trying to be cautious with Wood to prevent the shoulder problems from lingering through the season.
"We just felt, to be safe, [it would be better] to get him completely ready to go instead of waiting a couple of days to see how things were going," Sveum said.
"Part of the reason we wanted to DL him is because we don't want this to carry on. We want him to get strong for the rest of the season."
The move is retroactive to Wood's last appearance, which means he could return to active duty as soon as April 28.
To replace Wood on the roster, the Cubs recalled lefty Scott Maine from Triple-A Iowa. Maine was 1-0 with a 1.42 ERA in his five Minor League appearances. His arrival gives the Cubs a second lefty in the bullpen to go with James Russell, though prior to the game, Maine was not sure how he'd be used.
"I'm just expecting whatever they want," Maine said. "I'll be ready. One inning, two innings, five innings -- whatever."
Coincidentally, Wood's close friend and former teammate Sean Marshall, now the Reds' closer, was in Chicago for the weekend series between the Cubs and Reds. Speaking from the Cincinnati dugout before the game, Marshall said it's disappointing to see Wood having physical problems.
"I hate to see Woody hurt," Marshall said. "He's a great person. I played catch with him, really, all winter this year. I know he was feeling good when I was playing catch with him. Tough to see him have a setback."