The Case for a C.J. Wilson Bounce Back Season

I've been reading Nate Silver's The Signal and the Noise: Why So Many Predictions Fail - But Some Don't. For those of you who don't know, Nate Silver is the guy who invented PECOTA, a forecasting model he eventually sold to Baseball Prospectus (his former employer). The chapter I'm currently reading discusses a topic that I believe is relevant for fantasy players as they begin to prepare for the 2013 season.

Silver discusses the idea that "correlation does not imply causation", meaning that just because two variables have a statistical relationship with each other doesn't mean that one is responsible for the other. He uses the following as an example:

"For instance, ice cream sales and forest fires are correlated because both occur more often in the summer heat. But there is no causation; you don't light a patch of Montana brush on fire when you buy a pint of Haagen-Dazs".

While this particular example is a bit drastic, the principles can be applied to baseball statistics as well. A pitcher can throw more first pitch strikes while simultaneously increasing his K-rate, but it's possible that the reason he was able to do so was because he vastly improved a secondary pitch during the offseason, and not because he was pitching ahead in the count more. Sure, a pitcher throwing more first pitch strikes is correlated with having a higher K-rate, however, perhaps the pitcher fell behind in the count more than he had in the previous season, which in turn would have hurt his chances of striking out more batters. Follow? The point is it's easy to draw inaccurate conclusions from statistics and to mistake correlation for causation.

Additionally, it's easy to drown in the oceans of data now publically available through sites like Fangraphs and Baseball Reference. When looking at a player's year to year statistics, you try to spot trends to formulate an idea about how they might perform going forward. Unfortunately it's easy to get lost in the volume of less useful/relevant data, something Silver refers to as "the noise". The key to is to spot the "signal", what Silver describes as the piece and/or pieces of data most vital to providing insight into future results/performance. Anyone can look at a pitcher's BABIP and have a general sense of whether or not the pitcher was fortunate or unfortunate in the previous season. If you're in a competitive league, however, chances are that won't give you an edge on draft day. The key to gaining an edge is to remove as much of the noise as possible so you're only left with the most vital pieces of data. It takes time, but by doing so, you give yourself the best chance of locating the signal that will make your preseason preparation most effective. Luckily for you, I've taken the liberty to dissect Wilson's 2012 campaign in a Dexter Morgan-like fashion (figuratively speaking of course). Let's see what the autopsy tells us shall we?

C.J. Wilson is coming off of a disappointing 2012 campaign after posting a line of 13 W / 3.83 ERA / 1.34 WHIP / 173 K. Wilson finished the 2012 season as the 55th best starting pitcher on ESPN's Player Rater after finishing as the 12th best in 2011. Wilson's decline in performance can be summed up in two words: bone spurs. The Los Angeles Angels left-handed needed offseason surgery to clean up his pitching elbow but expects to be ready for spring training. Wilson claimed to have pitched with the injury for a "couple of months" and the numbers seem to support that statement.

Pre All-Star Break: 111.1 IP / 2.43 ERA / .202 BAA

Post All-Star Break: 91.0 IP / 5.54 ERA / .279 BAA

"I tried to make a million adjustments to get around it, to the point where now I'm standing on the first-base side, trying to get an angle because I can't throw sinkers anymore because my arm doesn't work right" Wilson was quoted in early October.

Looking at Wilson's pitch mix you can a see a pitcher trying to reinvent himself to some degree:

Year	Fastball %	Slider %	Cutter %	Curveball %	Changeup %
2011	53.2%	12.7%	13.2%	14.2%	6.7%
2012	51.5%	9.3%	16.4%	13.9%	8.9%

Wilson threw fewer fastballs, sliders, and curveballs while throwing more cutters and changeups to potentially compensate for his injury. My guess would be that Wilson elected to ease up on the slider and curveball as both offerings are the toughest on the pitching elbow (the slider being the toughest). Unfortunately for Wilson, this meant throwing his best pitch (the slider) less frequent while relying on his weakest offering (the changeup) more heavily.

We can look at Wilson's Pitch Type Linear Weights, which provides the total runs a pitcher has saved using a particular pitch on a "per 100 pitch" basis (i.e. runs saved with a slider over the course of 100 sliders thrown). To put the numbers into context, on a 100 pitch basis, a range is typically between +1.5 and -1.5 runs with a score of zero representing average, a negative score representing below average, and a positive score representing above average. While not a predictive statistic per se, it provides some insight into how the injury potentially affected Wilson's performance.

Year	wFA/C	wFC/C	wSL/C	wCU/C %	wCH/C %
2011	1.34	1.20	1.71	-0.58	-2.75
2012	-0.23	0.52	-0.66	0.92	0.12

Wilson's changeup was his weakest offering in 2011 (by far), however, he was forced to throw more of them in 2012.The effectiveness of Wilson's fastball, cutter, and slider were all compromised last season, especially the slider, which decreased by 2.37 runs saved per every 100 pitches, quite a significant decrease.

Intuitively this makes sense. If we look at Wilson's O-Swing% (pitches outside the strike zone a batter swings at) and SwStr% (percentage of strikes that a batter swung at and missed), Wilson wasn't able to entice as many batters to swing at as many pitches outside the strike zone or swing and miss more in general as evident by the decline in both his O-Swing% (29.9% to 25.5%) and SwStr% (8.3% to 7.6%). After losing the pre-injury effectiveness of his best pitches (fastball, cutter, and slider) Wilson wasn't able to pitch using his full arsenal.

Here is why I'm not worried though, and why I'm actually excited for Wilson heading into next season. He's going to be significantly undervalued in drafts. Some of our other rankers gave him a consensus ranking of 38^th, behind guys like Matt Moore, Brett Anderson, Jon Lester, Matt Harvey, Dan Haren, Jarrod Parker, and Tim Lincecum. Considering the numbers Wilson posted in his first two years as a starter (in Texas no-less) this came as quite the surprise.

Prior to 2012 Wilson averaged an ERA+ of 142 over 427 innings as a starter (fairly significant sample size). ERA+ is a pitching statistic that adjusts a pitchers ERA according to the pitcher's ballpark (in case the ballpark favors hitters or pitchers) and the ERA of the pitcher's league. An average ERA+ will be 100 and any score above 100 indicates the pitcher performed better than average and any score below 100 indicates the pitcher performed worse than average (Note: Wilson's ERA+ was 99 last season, so he was essentially a league average pitcher based upon this statistic).

To put Wilson's average of 142 into perspective, let's take a look at what some of the top pitchers posted last season from an ERA+ perspective:

Pitcher	2012 ERA+
Justin Verlander	160
Clayton Kershaw	150
David Price	149
R.A. Dickey	140
Cliff Lee	127
Matt Cain	125
Stephen Strasburg	125
Felix Hernandez	122

Wilson's ERA+ of 142 would have been fourth best behind only Verlander, Kershaw, and Price. As you can see, the guy has elite talent when healthy, so ranking him outside the top 35 doesn't make a whole lot of sense in my opinion.

Wilson has notched 200 innings in each of the past three seasons (workhorse) and averaged a line of 210 IP / 15 W / 3.37 ERA / 1.26 WHIP / 183 K, even taking into account last season's injury struggles.

The Angels have bolstered their bullpen for 2013 with the additions of Ryan Madson and Sean Burnett, which means Wilson might fall into a few more wins as well (Angels bullpen was ranked 22nd in ERA in 2011).

Additionally, while Wilson is a GB pitcher (50.3% groundball clip in 2012), the Angels will roll out the best defensive OF in baseball with Peter Bourjos in CF, Mike Trout in LF, and Josh Hamilton in RF next season. The slow-footed Mark Trumbo is being replaced with Mike Trout in LF. Think about that for a minute.

Wilson managed to decrease his fly ball percentage each year as a starter (33.5%, 31.9%, 29.9%) and his HR/FB ratio of 10.8% last season is an outlier looking at his previous three year average (6.7%). I would expect that number to regress towards his career norm, especially considering Wilson's groundball rate and considering the fact Wilson managed to post that ratio in Texas (consistently a top 5 hitter's park in terms of home runs each season).

A trend you worry about with a struggling pitcher is loss of velocity on his fastball (see Tim Lincecum, Dan Haren, Tommy Hanson). This wasn't the case with Wilson; however, as he posted his best average FB velocity since becoming a starter (91.6 mph) last season.

Finally, you can take comfort in the fact that Wilson bounced back nicely from a similar procedure previously (2008).

"I bounced back pretty well the last couple of years after that," Wilson said. "So I'm looking at that with a lot of optimism".

I think Wilson still has top 20 upside assuming a clean bill of health. His control, which has been an issue in the past, took a step back last season (BB/9 increased from 2.98 to 4.05), but I'm willing to chalk that up to the elbow.

If Wilson falls outside the top 25 pitchers off the board go ahead and thank your fellow league members because that noise you hear? That noise is the sound of profit my friend.

Sources

The Signal and the Noise: Why So Many Predictions Fail - But Some Don't
www.espn.com
www.fangraphs.com
www.baseballreference.com
www.mlb.com