Fernando Salas Passing A Kidney Stone Fixed Everything; Or Did It?

St. Louis Cardinals reliever Fernando Salas had a rough start to the season this year. Despite healthy strikeout and walk rates, opponents were hitting for a high average against the righty. The predictable results were more runs allowed by a reliever that offered stability in the closer role when the club most needed it early last summer.

On May 2, Jenifer Langosch reported on stlcardinals.com that the St. Louis coaching staff had identified a mechanical flaw that, when corrected, would see Salas return to form as the low-ERA reliever of 2011:

During an afternoon bullpen session on Wednesday, Salas was told of some discrepancies spotted between his delivery now and that motion during previous periods of success. That prompted some slight tweaking--mostly focused on getting Salas to have more exaggerated of a rotation--that the Cardinals hope will improve his fastball command.

The mechanical flaw detection and correction never gained traction as a narrative, probably because Salas continued to allow runs to be plated against him. On May 26, the Cardinals optioned Salas to Memphis. Matheny characterized the move as one "that we know is best for the long haul," as reported in the St. Louis Post-Dispatch.

"We need him. And we need to get him right," manager Mike Matheny said of Salas. "The best opportunity to do that is for him to get consistent work in a different environment."

At the time of the demotion to Memphis, Salas had thrown just 15.2 innings; in those innings, he had notched 21 strikeouts, issued nine walks, and allowed 23 hits. His ERA of 6.32 was fed by an opponent batting line of .333/.410/.449 which was not unrelated to their .438 BABIP against him.

On June 3, Matheny shared with the St. Louis media that Salas had passed a kidney stone and that the stone had been bothering the reliever since spring training. Langosch reported that the condition had not been previously disclosed to the media and identified the major question raised by the disclosure:

This news certainly begs the question of whether there is correlation between Salas' kidney stone issue and his early troubles.

Over the weekend, Langosch published a follow-up article on stlcardinals.com entitled "Salas feeling better after passing kidney stone." As is so often the cast with Langosch, this article is well worth reading. It details that Salas was concerned his "arm might be fatigued from his 2011 workload," that the kidney stone had been symptomatic since December, and that "Salas didn't necessarily understand the effect it was having on his performance earlier this year, because there wasn't much specific pain."

"I could pitch, but I didn't feel 100 percent," Salas said before Sunday's I-70 series finale against Kansas City. "I would throw a fastball and it would be flat. It had no life. I said, 'I don't know what's happening.' I didn't have any pain in my arm, but my fastball was flat. I didn't feel aggressive. I wanted to try, but my body wasn't working. But after my kidney stone [passed], when I woke up, I felt more and more energy. I'm more excited to play."

Regarding Salas's pitches, Matheny is also quoted by Langosch:

"It looks to me like he's finishing his pitches," manager Mike Matheny said. "There was definitely something going wrong before. We couldn't put our finger on it. He's making pitches now. He has to locate his fastball, and he has to have enough on his fastball to make his changeup good. That's what he's doing now."

I found the statements regarding Salas's fastball to be interesting. Salas says that his fastball was "flat" with "no life." Matheny seems to say Salas struggled with locating his fastball and did not have enough life on his fastball early in 2012 to make his changeup effective. These types of statements will be fuel for the media narrative fire. I'm certain that Al Hrabosky will remind us of Salas's kidney stone for the rest of the season. This being so, I wanted to see if the statements by Salas and Matheny were supported by Pitch F/X data.

The following chart contains information on Salas's fourseam fastball from his player card at Brooks Baseball. Salas throws a sinker on occasion, but does so rarely. Because of this, I take Matheny and Salas's statements to be on Salas's fourseamer.

The piece of data that immediately jumps out at me is the fact that Salas has been throwing his fastball at a higher speed on average than in 2011 throughout the 2012 season. Even though it has been even faster in the 26 times Salas has thrown it post-kidney stone than pre-kidney stone, this seems to undercut the observation of Matheny that Salas has to have enough on his fastball to make his changeup effective because Salas has had more on his fastball on average during 2012 than he did on average last season when he was so effective.

The next question is whether Salas has been throwing a "flat" fastball. I take this to mean that his fourseamer has not had the movement it had in 2011. In terms of vertical movement (V. Mvt.), it has and it hasn't. In April, the downward vertical movement on Salas's fourseam fastball was 0.79 inches less than in 2011. However, in May, it was dropping by 0.58 inches more than in 2011. Since passing the kidney stone, Salas has had 0.78 inches less downward vertical movement on his four-seam fastball.

This brings up an interesting question. Does a pitcher want more "rise" (or, less downward vertical movement) on a fourseamer? Even if more "rise" is what a pitcher desires, the data on Salas's fourseam fastball undermines his belief that it was consistently "flat" in terms of vertical movement in 2012 as compared to 2011. In April, Salas had less downward vertical movement than in 2011 and, in May, he had more.

Now let's take a look at the results of Salas's fourseamer.

Curiously, post-kidney stone passing, Salas has had opposing batters swing at a higher rate of pitches, has gotten fewer swings-and-misses, and has surrendered a far higher rate of balls in play. Of course, we're only talking about 26 pitches. In a few appearances, these numbers will likely look far different.

Here is a chart of his batted ball rates before and after the kidney stone left his system.

Again, Salas's swinging strike rate is far lower, his groundball rate is far lower, his line drive rate is far higher, and his fly ball rate is far lower. These won't continue, but they give you an idea of the batted ball luck at play here. In April, Salas surrendered a large share of liners despite a higher-than-2011 strikeout rate. This was very odd given the fact that high-strikeout pitchers typically give up weaker contact. In May, Salas saw his line-drive rate fall back to 2011 numbers even if his results didn't reflect this. Now, his liners allowed is again high, but his results are good. The gods of baseball a curious lot.

Even curiouser are Salas's post-kidney stone stats. He has tallied six innings, struck out only three batters, and walked two. Nonetheless, his ERA is a perfect 0.00 and opponents are hitting just .190/.261/.286 with a .222 BABIP. Is the result of batted-ball fortunes changing or passing a kidney stone?

The article by Langosch also notes that Salas was lethargic prior to passing the kidney stone.

The energy, Salas explained, is particularly a welcome return. He said that there were times earlier this season that he'd be sitting in the bullpen feeling like he was going to fall asleep. Salas couldn't pinpoint the reason for such fatigue.

"I didn't know what was happening," Salas said. "I was not myself. I didn't feel aggressive. Now I feel much better. I'm feeling good."

Athletes are very in tune with their bodies. They have to be; they earn a living based on elite physical performance. If Salas was sluggish, even sleepy, it seems highly likely it would have affected his performance. After all, recent studies show a connection between sleepiness and MLB career prospects. That being said, the numbers don't reflect a dip in performance. They don't really support the rapidly developing kidney-stone narrative, either. Nonetheless, I suspect Hungo will be bringing it up through the end of September, especially if Salas continues to generate results similar to those of the pitcher we saw in 2011.