Which St. Louis Cardinals relievers can Matheny trust in the late innings?

The St. Louis Cardinals bullpen had another rough game Thursday night. (Former?) setup man Carlos Martinez and closer Trevor Rosenthal conspired to blow a one-run Cardinals lead in the eighth inning. The Cards wound up losing a 6-5 heartbreaker to the National League’s top team.

Relief pitching is a high-wire act. Relievers usually come in for one-inning appearances—two at most. Over the course of a 162-game season, bullpenners typically notch between 65 and 80 innings. Both relievers’ innings-pitched totals in single appearances and full seasons are small samples, subject to wild fluctuation and outright defiance of peripherals far more than their starting counterparts.

But reciting "small sample size" and "reliever volatility," those most sabermetric of refrains, over and over has done little to bring late-inning serenity to Cardinals fans. Two of the club’s so-called "Big Three"—a group of relievers that consists of Rosenthal, Martinez, and Kevin Siegrist that was so named by manager Mike Matheny—have been big in the wrong way: runs allowed. And that has meant an undue amount of late-inning heartburn across Cardinaldom.

Trevor Rosenthal

Rosenthal looks like a different pitcher this season. There’s the velocity dip (even if it’s ticking upward as the weather warms). Rosenthal is inducing fewer swinging strikes (14.7% in 2013 vs. 13.3% this year). He is also notching fewer strikeouts (34.7 K% last year to 29.1 in 2014). But perhaps the most troubling Rosenthal trend is the doubling of his walk issuance, from a 6.4% rate a year ago to 12.7% in 2014. On top of all this, consider his strand rate: Rosenthal’s 67.5 LOB% is well below the 76.7% he posted in 2013 and the 74.4% MLB reliever rate for this season. Despite Rosenthal doubling his walk rate, he still has a very healthy FIP—thanks to his high K% and low homers allowed total—so there is some hope that his ERA will sink to FIP-like levels, so long as homeritis doesn’t set in with the rising temperatures of summer.

Carlos Martinez

While Rosenthal’s line gives some cause for hope, Martinez has been middling to the point of replacement level. His K% is four percentage points below the MLB reliever rate of 21.8% while his BB% is essentially league-average for a bullpenner. Martinez’s ERA is 1.22 above the MLB reliever rate of 3.60, even if his FIP is only 0.12 higher. This gap can be traced to Martinez’s eye-poppingly low 53.7% strand rate, which sits just over 20 percentage points below what MLB relievers as a whole have posted this season. Yes, there’s reason to believe that Martinez’s runs allowed should even out and bend his ERA in the direction of his FIP, but even then the righty with sexy stuff would only approximate a league-average reliever by ERA and FIP alike. This is a level of performance below what anyone expected, given his repertoire.

The Cardinals came into the season with a Big Three. Two months into the season, Siegrist is on the disabled list with a wrist/forearm strain and the two righties are allowing runs at concerningly high rates. Such is the nature of the relief corps. It leaves one wondering: Who can Matheny trust in the late innings?