Just What Happened to Casey Janssen?

Like it or not, this is the time of the year that we write about players like Casey Janssen. There aren’t a whole lot of alternatives. Janssen himself just signed on with the Nationals, to some degree replacing Tyler Clippard at the cost of $5 million guaranteed with a second-year mutual option. The Nationals aren’t expecting Janssen to be as good as Clippard. The Nationals shouldn’t expect Janssen to be as good as Clippard. There’s a reason why Janssen came relatively inexpensively. The year he’s coming off — it was a decidedly unusual year.

There’s a ready-made excuse: Janssen took a quick trip during the All-Star break, and he returned from said trip with food poisoning that cost him a told amount of weight and an untold amount of energy. We’ve all probably experienced food poisoning at some point, and though we’ve experienced varying degrees of severity, it makes sense that it takes a while to get back to feeling 100%. And Janssen didn’t have to get back to feeling 100% as a normal person; he had to get back to feeling good enough to succeed as a pitcher in the major leagues. Janssen’s first half was better than his second half. We don’t know how much the illness damaged Janssen’s statistics.

But the food poisoning might explain only part of the picture. He was fine early on, and he was fine toward the end. Physically, I mean. Yet the numbers are strange, given Janssen’s record. It’s easy to focus on the strikeouts. It’s not just the strikeouts.

We can begin with the strikeouts, though. They fell, from 24% to just under 15%. And while Janssen did struggle to strike anyone out after coming back from his vacation, if you take away the month immediately following the All-Star break, Janssen still managed a strikeout rate of just 17%. That’s a substantial drop, Janssen’s lowest by far since 2009, when he was still being tried as a starter.

And now take a look elsewhere, at another statistical category that tends to stabilize fast. Grounders! Janssen’s groundball rate fell, from 48% to just over 34%. His career mark, last season included, is 47%. Last year was his lowest rate by a wide margin, and though he especially struggled to keep the ball on the ground right after falling ill, again, you still see a big drop in the rate if you exclude a whole month of data.

Janssen lost strikeouts, and he lost grounders. His walk rate remained low, but we’re talking about big changes to two of the very most stable statistical categories. You’d think that maybe he changed his repertoire or approach, but, no, there’s not really anything there. His pitches all moved the same. His fastball lost a tick, but that shouldn’t be enough to explain what happened. Janssen’s 2014 was highly bizarre.

Let’s get you some perspective. Since 2002, we have more than 3,000 pairs of pitching seasons with at least 40 innings in consecutive years. In only 97 pairs did a guy’s groundball rate drop by at least 10 percentage points. In only seven of those did the guy’s strikeout rate also drop by at least seven percentage points. The pool of names:

• Casey Janssen, 2013-14
• Scott Stewart, 2002-03
• Tom Martin, 2003-04
• Takashi Saito, 2008-09
• Braden Looper, 2004-05
• Justin Miller, 2007-08
• Jason Hammel, 2012-13

With Janssen, we obviously don’t know what’s going to happen. Stewart was basically finished. Martin simply returned to his normal strikeout level; 2003 was the exception. Saito immediately bounced right back. Looper bounced back only a little in 2006. Miller was worse in 2009 than he was in 2008. Hammel, like Saito, is a success story.

Based on the Saito case, Janssen can get back to normal. It’s also not a thing the Nationals can take for granted. Now let’s dig in a little bit deeper. Obviously, we know that Janssen’s strikeouts came down. Yet in one interesting category, Janssen didn’t decline:

• 2013: 39% of pitches thrown while ahead in the count
• 2014: 40%

The league average has been right around 37%. Somewhat similarly:

• 2013: 30% of pitches thrown in two-strike counts
• 2014: 28%

There’s a small drop there, but it’s hardly remarkable. Janssen was still able to get ahead. He was still able to get into two-strike counts. He was just having trouble putting guys away. Hence:

• 2013: 21% of two-strike pitches generated strikeouts
• 2014: 14%

Janssen, last year, recorded 28 strikeouts. If you plug in 2013’s rate of two-strike pitches turning into strikeouts, that number jumps up to 40. But you can’t just assume that, because:

• 2013: 26% of two-strike pitches thrown in zone
• 2014: 37%

And there’s the worry. When he’s right, Janssen frequently tries to put guys away with fastballs or cutters in the vicinity of the edges. He tries to stay just off the plate, and a year ago, he was successful in doing so. This is how Janssen has been able to succeed as a reliever with diminishing heat. Last year, Janssen was missing a lot more often over the plate, and he acknowledged as much. It was a command problem — it’s virtually always a command problem — and this is an example of one case:

The problem with command issues is you can never count on them just resolving themselves. As Janssen loses more and more velocity, it’s going to be increasingly important for him to find his spots, and though his numbers were better last year before he fell ill, they were still diminished, relative to his recent record. Maybe there was something about the back injury that kept him out all of April. Maybe Janssen wasn’t right from the beginning, and his low first-half ERA was something of a mirage.

If there’s one thing even the worse version of Janssen can do, it’s throw strikes. He stayed in and around the zone, and his walk rate was miniscule. Now that he’s moving to the easier league, and what’s presumably the worst division in it, Janssen might find a more forgiving run of opponents. But Janssen, for a few years now, has been an unusual sort of closer. Even the usual sorts tend to have relatively short shelf lives. When the command starts to go, it’s everything. Last year’s Janssen comes with two potential explanations. The Nationals appear to be the most willing to believe them.