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07/30/12 7:29 PM ET

Led by Kelly, trio of Padres' prospects rehabbing

CINCINNATI -- There's no doubt pitcher Casey Kelly, regarded as the Padres' top prospect by MLB.com, is itching to pitch in a game.

Kelly probably never figured he would have to endure two consecutive days of rain that canceled games in the Arizona League to get in a game.

But Kelly, working his way back from a strained right elbow injury that sidelined him in April, hasn't been in a game since July 23. But he's scheduled to make his second rehabilitation outing on Monday.

Pitcher Joe Ross, a first-round pick in 2011, tossed two scoreless innings with short-season Eugene on Sunday. Ross has been on the disabled list since May with a sore right shoulder. Ross started the 2012 season with Class A Fort Wayne. He's now tossed three scoreless innings in two games for Eugene.

The Padres will gradually increase his endurance. Ross was the 25th overall selection in the 2011 Draft. Ross is rated as the Padres' ninth-best prospect.

Infielder Cory Spangenberg has missed nearly all of the last six weeks after he suffered concussion-like symptoms. Spangenberg, the No. 10 overall pick in 2011 who was playing at Class A Lake Elsinore, last played in a game on June 28 but suffered similar symptoms after diving for a ball. Before that, he last played on June 16.

Spangenberg, who was hitting .288 at the time, will play again on Tuesday or Wednesday. He's rated as the Padres' fifth-best prospect.

Padres call up Boxberger, put Thatcher on DL

CINCINNATI -- Brad Boxberger arrived at the Great American Ball Park on Monday sporting a new look: a beard, which he grew in the month that has passed since his first stint with the team.

Boxberger, a right-handed reliever, was promoted from Triple-A Tucson on Monday to take the place of reliever Joe Thatcher, who landed on the 15-day disabled list with tendinitis in his right knee.

Boxberger didn't just come to Cincinnati looking different, but he feels he's a much better pitcher than he was in June, when he walked seven in 6 1/3 innings in five games before heading back to Tucson.

"[Padres pitching coach Darren Balsley] and I talked about a couple of mechanical things, but I've been attacking hitters more and going after hitters earlier in the count," Boxberger said.

"It was too many [walks], so I'm definitely trying to cut those down this time around."

In 10 appearances in July with Tucson, Boxberger was 1-0 with a 0.77 ERA in 11 2/3 innings. Not only did he strike out 17 in that stretch, but he walked only three batters.

"Getting sent down isn't fun, but coming back this time, I know what to expect," said Boxberger, who has a 2-2 record and a 3.03 ERA in 34 games for Tucson.

That's a lesson manager Bud Black is hoping many of the young relievers who have been on the roster at varying times this season -- Miles Mikolas, Brad Brach, Nick Vincent -- have embraced: Go down, pitch better, come back to the big leagues better prepared.

"We've seen guys go back and come up, go back and come up and they're incrementally better," Black said

The reports from Tucson manager Terry Kennedy on Boxberger were good, Black said.

"He was throwing the ball extremely well in Tucson, so hopefully there's a carryover," Black said.

As for Thatcher, his balky right knee just hasn't responded to treatment enough in the last few days for the team to be shorthanded in the bullpen any longer.

"He just couldn't get over the hump with the knee," Black said. "This was the right thing to do."

Fruits of December trade all on Padres' roster

CINCINNATI -- For the first time this season, all four of the players the Padres received in the December deal that saw them send Mat Latos to the Reds were on the Padres' 25-man roster.

The addition of reliever Brad Boxberger to the roster before Monday's game against the Reds allowed for the Padres to have pitcher Edinson Volquez, first baseman Yonder Alonso, catcher Yasmani Grandal and Boxberger on the roster all at once.

Oddly enough, it occurred on the same day the Padres visited the Reds for the first of four games.

"It's definitely going to be fun," Boxberger said.

On Dec. 17, the Padres sent Latos to the Reds for the four players. Three of those players were in Monday's starting lineup -- Alonso, Grandal and Volquez on the mound.

San Diego manager Bud Black, who has been asked about the deal since it was made, in Spring Training and then when the Reds visited Petco Park earlier this month, said the newness of that particular trade has dissipated.

"I think a lot of the novelty of it has worn off, even going back to Spring Training, when we played the Reds over in Goodyear," Black said.

Black, as you might expect, still likes the trade and what it has brought the Padres -- a pitcher in Volquez who has a 1.2 WAR (wins above replacement), Alonso (0.5 WAR), Grandal (0.9) and Boxberger. The Reds have gotten nine wins out of Latos, who has a 1.3 WAR, according to Fangraphs.

"When both teams are happy, it's a good deal," Black said. "The Reds are happy with Latos and we have got some quality players, some depth. It's worked out for both sides."

Corey Brock is a reporter for MLB.com. Keep track of @FollowThePadres on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.