HOUSTON -- To clear space on the 25-man roster for Andrew Cashner, Thursday's starter, the Padres optioned right-hander Brad Brach to Triple-A Tucson.

Brach, 26, made 27 relief appearances for the Padres, going 0-1 with a 4.23 ERA in 27 2/3 innings. He last threw on Monday, pitching two scoreless innings in an 8-7 victory against the Astros.

"Like I told Brad last night, it's a process of becoming a Major League player," manager Bud Black said. "Just because you come up, that doesn't mean you're going to stay and settle into a 10-year career. There's learning points along the way."

The Padres' bullpen has been in a state of flux in recent days. On Wednesday, the team sent reliever Brad Boxberger down to Triple-A Tucson and recalled right-hander Nick Vincent.

"Brad will be back, just like a number of our relievers who have been sent out," Black said. "You'll see these names again in the Major Leagues."

Wells to start Sunday

HOUSTON -- Padres manager Bud Black will give 35-year-old Kip Wells his second start on Sunday at Colorado. Ross Ohlendorf, who started Monday's game against the Astros and threw 91 pitches, will move to the bullpen for the time being.

Ohlendorf was available for relief duty on Thursday, but Black said he hoped not to use Ohlendorf on two days' rest.

"That gives us a true long man," Black said. "A guy capable of throwing 50, 60 pitches in a relief role."

In his start on Tuesday, Wells went five innings, giving up five runs (two earned), striking out two and walking two. The right-hander threw 100 pitches, 60 for strikes, in his first Major League appearance since 2009.

"Better than I expected? No," Black said. "I have confidence in guys that are athletic and have the will to keep playing."

Black will continue to evaluate the Padres' makeshift rotation and adopt changes when necessary. San Diego has used 13 starting pitchers in its first 77 games.

Both Wells and Ohlendorf have experience in the bullpen. Wells has made 77 career appearances as a reliever, posting a 4.16 ERA in 119 innings. Ohlendorf has thrown 51 2/3 innings in 33 appearances out of the 'pen. His ERA as a reliever is 5.75.

Ohlendorf has come out of the bullpen twice in 2012, throwing 5 1/3 innings with a 3.38 ERA.

Worth noting

• Wednesday's game, which lasted 1 hour and 58 minutes, was the Padres' fastest game since a 1:58 game on July 1, 2008 at Colorado, according to ELIAS. Aaron Cook tossed a shutout in the Rockies' 4-0 victory.

• The Padres' bullpen has a 0.53 ERA in 17 innings in the last six games.

• Daniel Robertson, an outfielder at Triple-A Tucson, was named to the Triple-A Pacific Coast League All-Star team, which will play the International League All Stars on July 11 in Buffalo, N.Y.. Robertson, out of Oregon State, entered Thursday's game batting .328/.397/.419.

• The Padres will not play in Minute Maid Park again this season. With the Astros moving to the American League West in 2013, the Padres will only come to Houston for Interleague or postseason play after this season.

"I've grown to like this city," manager Bud Black said. "I like this ballpark, so I'm going to miss it in that regard. I like this city. It's Texas. Everything you think about Texas, you put Houston right there with all those definitions."