PITTSBURGH -- Pirates starter Zach Duke has answered questions about his season-long struggles for weeks now. On Saturday, however, those questions instead turned to his health.

Duke will miss his scheduled start Tuesday due to tendinitis in his left elbow, something the left-hander said has been bothering him this season but has now gotten to where it needed to be addressed medically.

"It's been something that's been bothering me for a little while now," Duke said. "It's to the point where I don't want to hinder the team anymore, and I want to get it right so I can be at 100 percent again."

After his rough start against Florida on Thursday, Duke talked with head trainer Brad Henderson about his inability to get his arm loose throughout his four innings of work. As a result, Duke took some strength tests -- which, according to Tracy, he "passed with flying colors" -- leading the Pirates to put Duke on anti-inflammatory medicine in the hope that medication will help the tightness subside.

While the elbow trouble is not necessarily the explanation for his inconsistency this year, Duke hopes that by taking some time off to treat it, he can begin to feel better on the mound and make strides in the right direction.

"It's just been something that over the past few weeks has been getting tight," said the left-hander, who is 3-7 with a 5.79 ERA this year. "It's time to do something about it."

Duke will do some light throwing Sunday to test out his arm and give the Pirates a better indication of whether they can expect the left-hander to miss more than just the one start.

"We will see how he's responding to the medicine that he's taking, and depending on how he's progressing, we'll see if, in fact, he just misses that start or if he'll miss more," Tracy said. "If it doesn't subside, we have to move on and do more testing. If it does, then obviously he can continue to progress, and we'll see where he's at as the week progresses."

Tracy did not announce who will take Duke's spot in the rotation, leaving open the possibility of a spot start by someone from Triple-A Indianapolis or that someone from the Pirates bullpen could fill in. That decision will likely be dictated by how the bullpen is used over the next few days and whether the Pirates expect Duke to miss more than one start.

Duffy disabled, Kata called: As expected, the Pirates placed center fielder Chris Duffy on the disabled list with a left ankle sprain. Duffy sprained the ankle against the Marlins on Thursday when he misjudged a fly ball. With the swelling yet to subside and Duffy still virtually immobile, the Pirates needed another bat for the bench.

"[Losing Duffy] is not something we could afford, but [getting the ankle healed] is something that's going to take a little time," Tracy said. "We want to get the swelling down and get the mobility back, so it's a move that we had to make."

The Pirates filled Duffy's roster spot with Matt Kata, who the club signed as a Minor League free agent June 13 after Kata opted not to report to Triple-A Oklahoma when the Rangers designated him for assignment.

Kata can play a variety of infield and outfield positions, though the Pirates are especially intrigued by Kata's ability to play second and third.

"We've got an extra infielder to fill a void," Tracy said.

In 70 at-bats for the Rangers this year, Kata hit .250 with two home runs and six RBIs. He then played 13 games for Triple-A Indianapolis, where he hit .265. The switch-hitter also played briefly with Arizona and Philadelphia during the 2004 and 2005 seasons.

Roster move: In order to make room for Kata on the 40-man roster, the Pirates designated Marty McLeary for assignment.

McLeary split time between the Pirates and the Indianapolis club this season. McLeary struggled in Pittsburgh, allowing seven runs in four appearances. After being sent down to Indianapolis on May 22, the right-hander allowed 17 runs in 38 1/3 innings and continued to struggle with his control, allowing nearly as many walks (25) as strikeouts (31).

All-Star invite? According to Tracy, the way Ian Snell has been pitching this season speaks for itself. The question is, however, has it spoken loudly enough to earn him a spot on this year's All-Star squad?

Snell's fate lies in those All-Star ballots turned in by players around the league and with St. Louis manager Tony LaRussa, who will announce Sunday who will represent the National League (you can watch the All-Star Selection Show live on TBS at 4 p.m. ET on Sunday). And let's just say the thought of an invitation has crossed the right-hander's mind.

"I'm not going to sit here and lie and be bashful about it," Snell said. "I've been sitting here and thinking about it for the past week, and if I make it, so be it. It's a great thing for me, a great opportunity for me. If I don't, I give it my best. I'm doing good, and the team's doing good."

Snell's performance over the first half of the season certainly justifies an All-Star invite. His 2.90 ERA is fifth-best in the league and he has made 12 quality starts. However, he may be hurt by a 6-5 record that would undoubtedly be more impressive if the bullpen hadn't lost some late leads and if Snell consistently had more run support. In Snell's five losses, the team has scored a total of five runs.

"Both [Tom Gorzelanny and Snell] record-wise should be better than where they are," said Pirates left fielder Jason Bay. "I don't think they get enough recognition around the league."

That lack of recognition and the fact that they play in a smaller market will likely mean only one of the two deserving pitchers will earn an All-Star selection.

Bay breather: For the first time this season, Bay's name was not in the Pirates' lineup before Saturday's game. Mired in a month-long slump, Bay's average has dropped from .314 to .266 since the beginning of June.

"It's been no secret I've struggled over the last month," Bay said. "I'm just looking forward to relaxing a little bit and [hoping] we're up 10-0 and I won't have to go in."

Bay and Tracy talked down in Florida about trying to find a time for Bay to take a much-needed break. And with the Nationals sending a right-hander to the mound Saturday, this seemed to be as good a day as any.

So how exactly did Bay expect entertain himself Saturday night?

"That question always comes up," the left fielder said. "Even [being the DH] in Seattle, I felt very uncomfortable on the bench. I guess I'll go down there and ask those guys what I'm supposed to do."

With Bay out, Xavier Nady made the start in left, while Ryan Doumit started in right field.

Torres tossing: Salomon Torres has bullpen sessions scheduled for Sunday and Tuesday in Bradenton, Fla., and may be ready to pitch an inning in a Gulf Coast League game as early as Thursday. The Pirates reliever went on the disabled list earlier this month with right elbow inflammation.

On deck: The Pirates close out a three-game series with the Nationals on Sunday at 1:35 p.m. ET at PNC Park. Left-hander Paul Maholm (4-10, 4.80 ERA) will take the mound for the Pirates against Washington lefty Mike Bacsik (1-5, 5.08 ERA).