SAN DIEGO -- The Padres on Monday announced that they have requested unconditional release waivers on shortstop Jason Bartlett, who has been on the 60-day disabled list since May with a strained right knee.

If granted his release, the 32-year-old Bartlett would become a free agent.

Bartlett, who signed a two-year contract worth $11 million before the 2011 season, played in 29 games prior to the injury. His contract included a vesting option for 2013 and a $1.5 million buyout. A career .271 hitter over nine seasons with Minnesota and Tampa Bay before coming to San Diego, Bartlett hit just .133 this season after batting .245 in 2011.

Manager Bud Black reflected on Bartlett's time in San Diego after the club acquired the former All-Star in an offseason trade with the Rays prior to the 2011 season.

"Turning back the clock a little bit, with Jason, when he signed with us, he was a guy who gave it his all every day he was out here," Black said. "Coming to a new club, coming to a new league, it took him a while to get his footing. We saw some of the good things he did with Tampa, but he maybe didn't carry that through stretches of games. I'll speak for the staff, I really enjoyed JB as a Padre, enjoyed our conversations about baseball."

With Everth Cabrera performing well at shortstop, and Alexi Amarista and Logan Forsythe contributing as the other middle-infield options, Black said the club felt it was time to move on from Bartlett and focus on the younger players.

"Moving forward, with our middle-infield situation the way it is right now, moving into the last part of this season and into September, I think that probably the playing time was going to go to these guys here and not to Jason," Black said. "I think we have to see what these three guys can do, and see what happens in September in the event that we bring up more guys."

Black said Bartlett's medical reports showed signs that he may be healthy enough to contribute to another club.

"I think he was getting better," Black said. "I think he has made great strides on how the knee feels and where he is physically, so that's a great thing for Jason moving forward wherever this takes him in the next step of his career."

Gregerson credits slider for stingy stretch

SAN DIEGO -- When Padres reliever Luke Gregerson has a good feel for his slider, the results speak for themselves.

With Gregerson riding a stretch of 18 consecutive scoreless outings (17 2/3 innings) entering Monday night's game against Pittsburgh, both the right-hander and manager Bud Black said that Gregerson's slider is as good as it has been at any time during the reliever's four seasons with the Padres. The numbers would seem to support that claim as Gregerson has held opponents to a .161 average with 19 strikeouts over the scoreless streak.

Both Black and Gregerson admitted that the slider escaped the 28-year-old last season, to a certain extent, and his strikeout total dipped from 93 in 2009 and 89 in '10 to 34. After working on his slider throughout last season and in the offseason, Gregerson said his slider is back to where he wants it to be.

"I've got a really good feel for it, and I don't mind throwing it pretty much at any point in time," Gregerson said. "It's been a confidence builder for me, especially last year, because I kind of lost it a little bit, but I feel like it's right back on point. I worked on it a lot last season and this offseason, and I don't think it was really until around the start of this season that I started to get the feel for it again."

Black echoed those sentiments and has regularly used Gregerson to protect the lead in close games, primarily in the eighth inning.

"He worked hard on a couple of different things," Black said. "He fooled around with the grip and with his release point. This year, there is a confidence that comes with throwing well, and with that, his feel came back."

With the renewed confidence in regaining his feel for the slider, Gregerson said his approach to throwing sliders can vary with the situation.

"Depending on the count, I like to put it a little more into the strike zone sometimes," Gregerson said. "If I'm behind, I'll look for something more down in the zone to get a ground-ball, or if it's a put-away pitch I'll kind of move it around a lot. It's just kind of whatever the situation dictates."

Layne relishing first exposure to San Diego

SAN DIEGO -- While rookie reliever Tommy Layne has only been in San Diego for a few days, so far he likes what he sees -- both of the team and of the city itself.

The rookie left-hander joined the Padres on Tuesday while the club was in Atlanta, having his contract selected from Double-A San Antonio, but his experience with San Diego has been limited to the current homestand that started on Friday.

"It's cool," Layne said. "I like San Diego. I really do. I'm telling people if they haven't been here, they need to come. I've only seen a small chunk of it, but it's beautiful."

Layne's performance has been similarly positive for the Padres, as the only lefty in the bullpen has struck out seven of the 12 batters he has faced, including all three in his Major League debut against the Braves. Part of that success may be due to Layne's familiarity with many of his current teammates, whom he played with in the Minors as well.

"I played with them all at Triple-A and Double-A -- it's nice to have familiar faces," Layne said. "Sort of helps to bridge that gap a little bit. But even if there wasn't, still doesn't matter you have to go out and make pitches -- you're in the big leagues!"

The 27-year-old Layne's enthusiasm about reaching the big leagues after six seasons in the Minors is clear.

"This is pretty cool up here -- it's a lot better than I thought it was gonna be," Layne said. "I saw a little bit of the Diamondbacks clubhouse when I was with them, but San Diego is a beautiful city -- I've had a lot of fun there."

Worth noting

• Right-hander Andrew Cashner will make a rehab appearance for the Triple-A Tucson Padres in Fresno on Tuesday and right-hander Anthony Bass will pitch in Tucson on Wednesday. Both are expected to throw about two innings, according to manager Bud Black.

• No starter has been announced for Wednesday's series finale against Pittsburgh. The spot vacated when Ross Ohlendorf was sent down to Tucson will likely be filled by a starting pitcher within the organization. Black expected to announce the starter on Tuesday.