ST. PETERSBURG -- Pitcher James Shields said Sunday that he and the other starters hate being taken out, but the bullpen the Rays have makes exiting a little easier.

Tampa Bay's relievers have been nearly untouchable recently, compiling a 0.38 ERA over the last 15 games, helping the Rays win nine of them.

During that time, opponents have just a .131 batting average and last scored on the bullpen in a 15-inning thriller against Oakland.

No reliever has been better than closer Fernando Rodney, who leads the Majors with 32 saves and has failed to convert just once this season. His streak of 20 consecutive innings without allowing a run is tied for the longest in the Majors by a reliever and just one short of the club record of 21, which was set by Joe Borowski in 2005.

Rodney faces tough competition to surpass that mark as lefty J.P. Howell also has a scoreless inning streak of 20 after pitching two frames Saturday, throwing just 18 pitches and striking out four.

"He's starting to get that movement on the fastball that he had," Rays manager Joe Maddon said. "You can see the breaking ball, it's much better depth and they're getting worse swings on it."

The success is a welcome sight for Howell, who struggled from mid-May through mid-June. In a span of 12 appearances that began May 12, he allowed 11 runs in eight combined innings of work. Since then, he hasn't allowed a run with 18 punchouts.

Maddon said an increase in fastball velocity, which has more consistently been at 86 and 87 mph, have made the difference.

"You can just see the hitters not on him like they had been last year," Maddon said. "They're not getting the same quality swing they had last year, which means that the deception is back, the movement is better."

Zobrist exits early vs. O's with upper back spasms

ST. PETERSBURG -- Rays second baseman Ben Zobrist was removed from Sunday's game against the Orioles prior to the start of the fourth inning due to upper back spasms.

The team announced the injury was not believed to be serious. He finished the day 0-for-1 at the plate.

Will Rhymes took his place in the lineup, striking out in his first at-bat on the day.

Zobrist has been one of the team's more consistent hitters, batting .250 on the season with 12 homers and 42 RBIs.

Rehabbing Longoria back in lineup in Triple-A

ST. PETERSBURG -- Injured Rays third baseman Evan Longoria was back in the lineup for Triple-A Durham on Sunday, making his eighth rehab start for the club.

Out since April 30 with a partially torn left hamstring, Longoria has struggled at the plate for the Bulls, going just 4-for-27 with six walks and 2 RBIs. Each of his appearances has been as the designated hitter, and he isn't likely to see action in the field when he does eventually return to the Majors.

"We're just relying on the people there watching him, and him," Rays manager Joe Maddon said of Longoria's progress. "We're still gonna be patient with that until we get all the right answers."

Longoria missed Tuesday's game because of "soreness" but has been in the lineup for Durham's last three games, going 1-for-10.

He will be re-evaluated Monday by the Rays and could possibly be back for the team's upcoming series against the Blue Jays, which starts Tuesday, but Maddon said the chances of that happening are "50-50."

"How he does [Sunday night] would really matter, he's gone several days in a row right now," Maddon said. "I think the bigger issue from what I'm hearing is more that how he feels at the plate than his body... I just don't know that he feels good in a baseball way hitting yet."

In 23 games prior to the injury, Longoria was batting .329 with four homers and 19 RBIs.

After throwing a three-inning simulated game Friday, Jeff Niemann is set to begin a rehab assignment with Class A Port Charlotte on Wednesday. The assignment is expected to be at least four starts, to help stretch him out so he can throw 100 pitches.

Niemann was struck in the leg by a line drive May 14, resulting in a fracture. He was 2-3 with a 3.38 ERA and 30 strikeouts prior to the injury.