Last October, Shelby Miller became something of a mystery. After spending the year in the Cardinals rotation and developing into one of the league’s best young hurlers, Miller became nothing more than an active roster cheerleader in the postseaosn. He pitched one inning in the Cardinals five game NLDS victory over the Pirates, then didn’t enter a game in either the NLCS or the World Series. All told, St. Louis pitchers threw 152 innings in October, but even with that workload, the Cardinals managed to give 151 of them to pitchers not named Shelby Miller.

He insisted he wasn’t hurt. If he was injured, the Cardinals could have simply replaced him on the playoff roster with someone else, someone they would use. The fact that they carried him for all three postseason series suggests that it wasn’t a predetermined plan to not use him and supports Miller’s assertion that he could have pitched. Mike Matheny didn’t just trust him in any kind of meaningful situation, and the Cardinals didn’t play many low leverage innings in October.

The Cardinals didn’t say much publicly about their decision, but it was reported over the winter that Miller was dealing with some shoulder fatigue in September, so despite Miller’s claims that he felt good, there might have been a physical reason for his absence. However, with an off-season of rest, the Cardinals have put Miller right back into their plans, and were presumably hoping that a little rest would allow Miller to go back to what he was during the regular season last year.

Well, apparently, an off-season of rest hasn’t fixed anything, because the Shelby Miller that has taken the mound for two starts in April mostly looks like the September version who the Cardinals decided wasn’t up to pitching meaningful innings in October.

Between April and August 24th, Shelby Miller made 25 starts last year, throwing 140 innings and posting a 3.32 ERA/3.60 FIP/3.49 xFIP. He struck out 26% of the batters he faced in those starts, and by limiting walks as well (7% BB%), he was a quality starter every five days for the Cardinals. In 20 of those 25 starts, Miller posted an xFIP below 4.00, so while every pitcher experiences game-to-game BABIP and HR/FB fluctuations, Miller’s core profile remained pretty steady each time out.

Then came his August 30th start. From that point on, he made seven starts and posted an xFIP over 5.00 in six of those seven performances, only having one decent performance in which he induced a bunch of ground balls from the Brewers. The strikeouts went away almost entirely, and his K/BB ratio for the month was 18/16 in nearly 34 innings. The Cardinals weren’t just worrying for no reason. The September version of Shelby Miller was pretty terrible.

And the version that has taken the hill for his first two starts of April looks much the same. In his first start, Miller posted an xFIP of 6.16; his second start wasn’t much better at 4.84. 51 batters faced, six walks, seven strikeouts.

So, what’s changed? Why did Miller go from a strikeout machine to a pitch-to-contact guy who struggles to put batters away? Well, for one thing, hitters have stopped swinging and missing.

Or, for those of you who prefer tables to graphs; his monthly rate of whiffs per swing since the start of last year.

Month Hard Breaking Offspeed 13-Apr 23.2 20.0 – 13-May 24.9 17.8 – 13-Jun 27.2 17.1 21.1 13-Jul 23.3 22.2 20.0 13-Aug 26.4 22.6 31.8 13-Sep 16.3 – 16.7 14-Apr 13.6 14.3 –

In the eight starts he’s made since August 30th of last year, he’s thrown 110 breaking balls; hitters have swung and missed at two of them. Same thing with his off-speed stuff; 60 pitches thrown, two swings and misses. They’re hitting his fastball more as well, but the drop-off isn’t quite as dramatic as it is with the secondary stuff. However, that doesn’t mean the fastball isn’t the culprit.

For the first five months of the season, Miller’s fastball generated essentially an even number of balls and called or swinging strikes; 31% balls, 32% non-foul strikes. Since August 30th of last year, he’s at 35% balls, and only 23% called or swinging strikes. Miller is still a predominantly fastball centric pitcher, and he’s simply not getting ahead in the count as often as he was last year. If you’re pitching in even or neutral counts, there’s fewer reasons for hitters to chase your secondary stuff.

For his first 25 starts last year, opposing batters swung at 41% of the curveballs he threw; since then, 29%. It was called a ball just 36% of the time he threw it for his first 25 starts of 2013; it has been called a ball 48% of the time he’s thrown it since. Miller’s curve is designed to be chased, and when it’s working well, he throws it at the bottom of the strike zone, trying to get hitters to swing over top of it. Here is where he’s thrown his curveballs this year.

They’re either nowhere close to the zone and easy takes for a ball, or hanging meatballs ready to get whacked. And it doesn’t help that the velocity on his curve has taken a plunge as well. During his good stretch last year, his curveball sat around 80; over his last eight starts, it’s sitting at 78. His fastball velocity is down as well, but not quite as much as the curveball velocity, and Miller needs his curveball to be a good pitcher.

It’s easy to write off his first two starts as just two starts, but this isn’t a two start thing. This is now an eight start thing. Since 8/30/2013, Miller’s line:

45 IP, 46 hits, 22 walks, 25 strikeouts, 4.69 ERA, 6.03 FIP, 5.47 xFIP

Right now, Shelby Miller is not a good pitcher. He hasn’t been for a while, and the Cardinals should absolutely be concerned. Perhaps his problems are fixable, and this is a thing will work itself out while he’s on the mound; they should hope so, because an off-season of rest didn’t seem to do any good. With pitchers who have sudden decreases in performance and rumors of shoulder problems, though, it’s hard not to think this might eventually require a trip to the surgeon’s table.

For both Miller and the Cardinals, one hopes that this is the kind of issue that can be fixed with some mechanical tweaks or other non-invasive procedures, but this version of Shelby Miller isn’t very good, and unless he flips a switch sometime soon, they’re going to have to start looking for alternatives.