Cain, 23, impressed Brewers coaches when he filled in for some injured outfielders during Spring Training but saw his season derailed by a left knee injury in April. He was limited to 60 games at three levels of Milwaukee's farm system and batted .218 with a .277 on-base percentage.
"When you play with an injury all year, it can make you apprehensive, and it did," Brewers farm director Reid Nichols said. "He had doubts on his knee. He was probably playing a step short the whole time and had a little lack of confidence in what he could do physically. That's normal when you can't go the way you want to go. There's no doubt he's a good player. He just has to get that knee as well as his other one."
Cain is currently making up for lost time in the Arizona Fall League. Through 17 games, he was hitting .242 with a .375 on-base percentage and 14 runs scored as the Peoria Javelinas' leadoff man and was tied for ninth in the league with 13 walks. Brewers general manager Doug Melvin got a firsthand look last month when club officials gathered in Phoenix for organizational meetings.
"It looked like he was back to full speed," Melvin said. "He covered a lot of ground in the outfield and played good defensively. At the plate, he got a lot of walks. He still needs development time, but we liked what we saw with him. He just needs to stay healthy."
If not for the injuries that plagued him in 2009, Cain might have entered this offseason as one option to man center field for the Brewers in '10. Instead, the team traded for Minnesota's Carlos Gomez, who is also just 23 years old and is under team control for four more years. The Brewers also are high on Logan Schafer, another center-field prospect, who played below Cain in the system in 2009 but won the organization's Minor League Player of the Year honor.
Cain topped out at Double-A Huntsville in 2009. Melvin said his 2010 assignment wouldn't be discussed until Spring Training.
"We're feeling pretty good about our center-field situation," Melvin said. "There are guys who have to work on their hitting a little bit, but in terms of defense and athleticism, we like what we have."
Rivas, who turns 24 on Dec. 20, was 13-7 with a 2.98 ERA at Class A Brevard County in 2009 and surged in the second half to win the Robin Yount Award as the organization's top pitcher. He was at Miller Park to accept the award in September.
In the second half of the 2009 season, Rivas posted a 2.26 ERA in 71 innings.
"He pitched really well and showed us his durability," Melvin said. "His strikeout rate was up. He got stronger and pitched better in the second half."
The Brewers also claimed Boston catcher George Kottaras off waivers on Wednesday. With all of the additions, the team has 36 players on its 40-man roster.
Generally, players who signed when they were 19 or older must be protected on a 40-man roster after four Minor League seasons. Players signed when they were 18 or younger can play five seasons before they need protection.
Unprotected players can be plucked away by other teams in the Rule 5 Draft, held on the final day of the Winter Meetings (this year it's scheduled for Dec. 10 in Indianapolis). Teams get $50,000 for each player they lose in the Major League portion of the Draft, and get a chance to take that player back for half the original cost if his new team does not keep him in the Majors for at least 90 days.
The Rangers' Josh Hamilton (who went from the Cubs to the Reds in 2006) and the Mets' Johan Santana (Astros to Marlins in 1999) are among the gems of past Rule 5 Drafts.
The most notable players not protected by the Brewers on Wednesday may have been power-hitting outfielder Brendan Katin and left-hander Chris Cody.
Katin, who will be 27 in January, led Nashville with 92 RBIs and tied for the team with 24 homers but also struck out 164 times in his fourth consecutive 100-whiff season and didn't get a callup to the Majors, even after the Brewers lost right fielder Corey Hart to an appendectomy in early August. By that time, Katin was coming off a .195 average in July, and he went all of August without hitting a home run.
Cody turns 26 next month after going 13-9 with a 3.90 ERA between Double-A Huntsville and Triple-A Nashville. He did not finish the year particularly strong, with a 7.00 ERA (35 earned runs in 45 innings) over his final nine starts. The Brewers acquired Cody in a 2007 trade that sent disgruntled reliever Jose Capellan to the Tigers.