(Photo by Dilip Vishwanat/Getty Images)

St. Louis Cardinals closer Trevor Rosenthal had another blown save last Wednesday night, bringing him to three blown saves on the season in 19 save opportunities. Is this just a rough patch or troubling signs for the future?

Rosenthal has four pitches in his repertoire – a four-seam fastball, change-up, slider and curve – but relies very heavily on his fastball (76 percent of all pitches thrown this season). And according to Pitchf/x data, his velocities with each do not appear to ring any alarm bells.

His command, on the other hand, leaves a lot to be desired.

This season he has pitched 29.1 innings, striking out 37 batters and walking 16 more. Last season he struck out 108 in 75.1 inning of work, walking just 20 batters. That’s a huge decrease in strikeout-to-walk ratios from year to year, most of the which can be attributed to batters swinging at fewer pitches outside the strike zone.

But even more troubling than the command is that his fastball is no longer an effective weapon. According to Pitch Type Linear Weights, which represents the amount of runs a pitcher saves with a particular pitch over the course of 100 pitches thrown, Rosenthal’s four-seamer stood at a well above-average 1.31 in 2012 during limited action, was above average last season (0.60) and is exactly average  (0.01) this season.

Plus, to make matters even worse, his fastball is not inducing as many grounders as it once was and is instead jumping off the bat (line-drive percentage) more often than ever.

Line drives carry a slugging percentage almost four times that of grounders, so with more line drives in play we can expect Rosenthal’s ERA to balloon over its current 3.99 mark.

2014 NL
Groundballs 0.236 0.236 0.257 0.236
Flyballs 0.159 0.156 0.481 0.074
Line Drives 0.658 0.650 1.006 0.635
Bunts 0.324 0.324 0.324 0.324
Source: Baseball-Reference

The future is not bright for the Cards’ closer: an average fastball that is being pounded plus a lack of command is certainly a recipe for disaster.