What's Wrong With the Diamondbacks' Ian Kennedy?

Ian Kennedy was legitimately in the running for the National League Cy Young award last season.  He was a big reason why the Arizona Diamondbacks made a surprise run to win the division.  He is also a big reason why the team has faltered this year.  Such is the case with pitchers.  If a team develops an ace then suddenly loses him, it's hard to recovery from that.  Most times you see this with injuries, but with Kennedy, no injury has been diagnosed.  The Diamondbacks have simply lost him even though he's on the mound every fifth day for them.

But is that true?  Are there any indications that something more might be going on?  Let's take a closer look, but first let's get some baseline information on Kennedy.  To judge whether a pitcher is hiding an injury takes much more than a look at the numbers, but that's all we have, so we need to look at ALL the numbers.



Kennedy was drafted by the New York Yankees 21st overall in 2006.  They had high hopes for the young righty out of USC.  Kennedy progressed through the Yankees' system quickly, posting a 1.96 ERA in 2007 combined as he rocketed through Class A, AA, and AAA in one season.  He made his Major League debut on September 1, 2007.  In those first few appearances with the Yankees in 2007, New York thought they had the real deal.  Kennedy started three games and posted a shining 1.89 ERA.  He kept the ball in the park and struck out enough batters to get by.

However, in 2008 things changed.  He started eight games, appeared in nine, and had an unsightly 8.17 ERA.  He had a rough go, but things were about to get much worse.  In the spring of 2009, Kennedy learned he had an aneurysm in his pitching arm.  It would require surgery and months of rehab to comeback.  Kennedy didn't think he would pitch a single game for the Yankees in 2009, but he did.  He came back toward the end of the season, made one appearance for one inning, and finished the year with a 0.00 ERA.

The next season was supposed to be a fresh start for Kennedy, and it ended up being so in more ways than one.  Kennedy became a key piece in a three-team trade that included other names like Max Scherzer, Edwin Jackson, Phil Coke, Austin Jackson and Curtis Granderson.  It was a huge trade - one that has widely been considered good for all three teams.  Kennedy was starting over in the desert.

He started 32 games in 2010, and while his record was disappointing, he showed some of the talent that would break through in 2011.  In 2010, Kennedy had a 3.80 ERA and had reduced his walk rate to the lowest ratio in his career.  But the real break-out season was last year.  In 2011, Kennedy finished fourth in National League Cy Young voting.  He established himself as a legitimate ace, and he helped the Diamondbacks win the NL West almost out of nowhere. During the 2011 season, Kennedy posted a 2.88 ERA, won 21 games, and reduced his walk rate even further - to just 2.2 walks every nine innings.

But something happened in 2012.  The Diamondbacks had huge expectations heaved upon them by fans and the media.  Ian Kennedy was not immune to personal expectations as well as the team expectations.  He was an ace, he had to pitch like an ace.  But it quickly became apparent, he wasn't going to do that.

In the first half of this season, Kennedy had a 4.26 ERA.  This in and of itself was concerning, but he had the second half to right the ship and help lead Arizona back to a division crown.  However, so far in the second half of the season, Kennedy has actually seen his ERA increase.  In ten second half starts, Kennedy has a 4.28 ERA.  Overall, he is sitting on a 4.27 ERA.  So what has caused this?  Bad luck?  A regression to the mean?  Maybe an injury?

If we were to take the bad luck excuse and run with it, we may point to Kennedy's high BABIP of .306.  It's 27 points higher than his career average and 36 points higher than what he put up last season. We could sit back and assume hits are just falling in when they otherwise may not have.  It's a solid argument to make until you look beyond BABIP.

First, let's examine his FIP.  This measure essentially take defense out of the equation and lets us judge a pitcher on what he can control.  If Kennedy were simply unlucky and had maybe a poor defense behind him, we'd see an FIP lower than his ERA.  However, Kennedy's FIP is actually higher than his ERA at 4.31 verse 4.27.  While it's not much of a difference, Kennedy's FIP certainly doesn't indicate bad luck.  Digging deeper, we can also see Kennedy's fly ball percentage is considerably higher than last season (42.4% this year against 39.5% last year).  Therefore, it should come as no surprise that his HR/9 ratio is also higher (1.39 this season, 0.77 last).  The more fly balls given up, the more likely a pitcher is to allow home runs.  There is no singular nail in the coffin to the bad luck argument, but numbers beyond BABIP seem to indicate there is something more going on.

So let's address a potential regression to the mean.  First, let's find what the mean is for some important statistics and compare it with this year's numbers and last year's numbers.  Maybe last season was a fluke.  The mean will be the first number listed, 2012 numbers will be in red, and 2011 numbers will be in blue:

BABIP: .279 - .306 - .270
LOB%: 74.9% - 75.0% - 79.2%
HR/9: 1.08 - 1.39 - 0.77
BB/9: 2.88 - 2.35 - 2.23
GB%: 37.2% - 36.0% - 38.6%

These numbers are starting to give us a clearer picture.  It would seem that Kennedy simply had a great season and is truly regressing back to his career averages this year.  Baseball has a way of doing this to players.  Ryan Dempster is having a breakout season (less so now that he's been traded from the Cubs to the Rangers), but there is a good chance that next season his numbers revert back to what we're used to.  Kennedy, though, is young enough to think that last season was a true progression toward dominance.  We saw what he could do with the Yankees in their minor league system and his short stint in 2007.

So if Kennedy had a break-out year on his way to being a dominant pitcher, assuming he really isn't regressing to the mean, could he be injured this year and trying to hide it?  Pitchers, and baseball players in general, do this all the time.  It's so ingrained in the minds of professional athletes to never miss any time that they won't.  Even to the detriment of their teams, they will keep playing while injured.  While it is impossible to know for sure if Kennedy is injured, we can look at some common themes that come up with injured pitchers; velocity and control/pitch movement.

Let's start with velocity.  According to Brooks Baseball, who run a fabulous PitchFX program, Kennedy has seen a dip in velocity this season.  He averaged 89.6 mph on his fourseam fastball, but this season his average was 89.2 mph.  That's not a big dip, but when you look at the per start velocity of all of Kennedy's pitches over the course of his career, you can see a noticeable change this season.  As provide by Brooks Baseball, here is Kennedy's velocity chart tracking the speed of all his pitches over the course of a season and over the course of his career:

Courtesy of Brooks Baseball
Let's first look at the fourseam fastball (black).  You can see that early in the year Kennedy was taking it easy on his velocity, but as the season progressed, he picked it up and it spiked at around 95 mph.  Since that point though, there has been a clear decline in Kennedy's velocity on the fourseam fastball.  The decline has been consistent as well.  That's the first red flag. We see almost an identical trend with the cut fastball (dark red), the change up (blue), and the curveball (yellow).  These are all red flags that may indicate fatigue or injury.

These trends in 2012 would be far less concerning if each of the previous four or five seasons showed a similar trend toward the end of the year.  It's not uncommon for a pitcher to experience fatigue naturally toward the end of a season.  What is uncommon is for a pitcher who has never had that issue, a pitcher who has actually increased velocity as the season went on, to suddenly see a dramatic drop-off.

How about control and pitch movement then?  We know Kennedy's control is still there based on his walk rates.  He did not suddenly see a jump in HBP or BB this season.  Let's rule out control as an issue that may identify injury.  Pitch movement is a completely different story.  See below:

Horizontal movement - Courtesy of Brooks Baseball

Kennedy's horizontal movement (the side to side movement) of his pitches this season has been less drastic.  In years past, we see a wide spread on the movement in inches.  This season, the movement numbers are far more clustered together.  The same is true with the vertical movement below:

Vertical movement - Courtesy of Brooks Baseball

The reduced movement means that Kennedy's pitches are flattening out.  If he is getting less movement, it becomes easier for the batters to see the pitch and hit the pitch.  This explains the increased rate of fly balls and the increased rate of home runs allowed this season.  A pitcher experiencing arm pain or discomfort is going to struggle with getting his pitches to move.

I think we can all but rule out the bad luck argument as a reason for Kennedy's struggles this season.  I'd like to rule out the regression to the mean argument as well based on Kennedy's age and the flashes of greatness he's shown even before last season, but I'm not quite ready to discount that argument altogether.  The injury argument is intriguing and it's something I'm sure the Diamondbacks have looked into and talked to Kennedy about.  The charts above are telling.  They show something is clearly different this season.  If that difference is an injury, we may never know.  What we do know is Kennedy has seen a drastic reduction in his velocity and movement as the 2012 season has wore on.

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