Heavily used relievers now facing challenges

Predicting the performance of relief pitchers has traditionally been one of the most dicey undertakings for scouts and general managers. Performances from one season to the next tend to be up and down, down and up.

One logical explanation is that when they're throwing well, it follows naturally that they'll throw often. And that when they throw often, the impact may be felt the next year.

There were seven relievers who appeared in more than 75 games in 2013; let's take a look at how they've fared so far this year. Spoiler alert: Six of them have not been able to replicate their success from a year ago, five have dealt with injuries or illness and one changed teams in the offseason.

Joel Peralta, Rays. ERA: Up from 3.41 to 4.26.

After leading the Major Leagues with 80 appearances last season, Peralta's numbers have gone downhill. After opponents hit .184 against him in 2013, they are now at .244 this season. However, a deeper look defies easy categorization. Through May 9, Peralta's ERA was 7.63. In his next 35 outings, he posted a 1.95 ERA. In Peralta's past 10 games, his ERA was 7.59.

Peralta also spent time on the disabled list with an illness immediately after the All-Star break.

Brad Ziegler, D-backs. ERA: Up from 2.22 to 3.49.

After making 78 appearances in 2013, the sidearming right-hander didn't come close to putting up the same numbers this season. But there were extenuating circumstances. In his first 42 appearances, Ziegler's ERA was 2.45. At that point, he has since revealed, he began to experience discomfort in his left knee. In his next 26 games, Ziegler's ERA was 5.06.

Ziegler was scheduled for season-ending surgery Tuesday to remove frayed cartilage.

Cody Allen, Indians. ERA: Down from 2.43 to 2.15.

Allen was tied for third in MLB with 77 appearances last year, and so far, he has been the outlier. Not just his ERA, but his opponent's batting average (.233 to .193) and WHIP (1.25 to 1.09) have improved.

After blowing just one save opportunity all year, Allen was unable to hold a lead in back-to-back appearances on Aug. 31 and Sept. 2. It's too soon to tell whether that's just a hiccup or a sign he could be tiring.

Ronald Belisario, White Sox. ERA: Up from 3.97 to 5.57.

After leading the Dodgers with 77 appearances in 2013, Belisario was non-tendered by Los Angeles and signed with the White Sox as a free agent. He was used briefly as a closer earlier this season, before being moved back to a setup role. Belisario's lofty ERA is largely the result of two appearances, in which he gave up nine earned runs in a total of one-third of an inning.

Belisario's secondary stats are more in line from 2013 to '14, with his opponent's batting average rising from .274 to .291 and his WHIP actually dropping from 1.47 to 1.38.

Matt Lindstrom, White Sox. ERA: Up from 3.12 to 4.23.

After pitching in 76 games last season, Lindstrom opened this season as Chicago's closer. He was 6-for-9 in save opportunities and posted a 3.32 ERA, before undergoing left ankle surgery that sidelined him for nearly three months. In nine appearances since being activated, Lindstrom's ERA is 6.23.

Paco Rodriguez, Dodgers. ERA: Up from 2.32 to 4.35.

After becoming the first player from the 2012 First-Year Player Draft to make it to the big leagues, Rodriguez had a stellar 2013 season. In 76 appearances, he allowed just 30 hits in 54 1/3 innings, held opponents to a .164 average and posted an 0.90 WHIP.

This season has been a struggle for Rodriguez, even seeing him optioned to Triple-A Albuquerque. Three days after being recalled on Aug. 2, he was placed on the DL with a left shoulder strain. The Dodgers are hoping to have Rodriguez back before the end of the regular season.

Tanner Scheppers, Rangers. ERA: Up from 1.88 to 9.00.

After making 76 relief appearances last year, Scheppers came back this season as the Rangers' Opening Day starter. After four starts, he was shut down for more than a month with elbow inflammation. Scheppers returned as a reliever and pitched four more times, before going back on the DL.

Team officials and Scheppers have both said they don't believe moving to the rotation caused his problems.