The deals are a reaction to a couple of recent developments. The Rockies optioned left-handed rookie Franklin Morales to Colorado Springs so he can correct issues that led to a poor start. Also, the Rockies lost righty reliever Kip Wells to a blood clot in his throwing hand.
De La Rosa, who was 3-0 with a 1.64 ERA in four starts at Triple-A Omaha, is the long-rumored player to be named in the deal that sent right-handed reliever Ramon Ramirez to the Royals. De La Rosa, 27, was 11-16 with a 5.64 ERA in 36 games, including three starts, for the Royals in 2006 and 2007.
"It's a good opportunity for me," De La Rosa said. "It's nice to get back in the Major Leagues."
The Rockies saw De La Rosa last May 18, when he held them to two runs and six hits in 6 1/3 innings of an eventual 5-2 Royals victory. De La Rosa struck out two and didn't walk anyone.
"I pitched there before and I liked it," said De La Rosa, whose expected start Saturday will be against a fellow Mexican pitcher, the Dodgers' Esteban Loaiza.
"We've been on him for a while and we've got people that like him," Rockies manager Clint Hurdle said. "He's a big left-hander with a big arm. Everybody's been waiting for him to kind of firm things up and become more consistent.
"They [the Royals] sent him down and his last three starts have been about as good as anything you'd want out of the kid. He's got a handful of walks, 17 strikeouts. It's been pretty impressive since he's been down in a starting role. We'll see how that plays out."
Grilli was in his fourth season with the Tigers and third in their bullpen since signing as a Minor League free agent with the same team for which his father, Steve, pitched in the 1970s. He has allowed five runs on 12 hits in 13 2/3 innings this season, walking seven and striking out 10.
"I'm going to a team that I'm trying to help, and they've got some good things going on there," Grilli said. "I feel like I'm at least not going to a team that's rebuilding, which is a great thing. Hopefully I get to hit a little bit, which is going to be pretty fun."
Grilli, 31, was a Giants first-round Draft pick in 1997 and has pitched in the Majors for the Marlins (2000-01), the White Sox (2004) and the Tigers. Rockies front office assistant Marcel Lachemann, a key voice in pitching matters, talked with Tigers pitching coach Chuck Hernandez before the clubs made the deal.
"We've seen him some in the past, and he's a versatile guy out of the bullpen," Hurdle said. "He's pitched multiple innings. He's got a pretty live fastball, some thump to it -- 92-94 [mph]. We have some people in our organization that really like him."