Justin Verlander's slider and curveball reveal mechanical changes in his delivery

I have a confession: I lied to you. Well, 'lied' probably isn't the most accurate term. I misled you. Like Dave Dombrowski does with every rumor that crosses his path, I chose my words carefully in order to pull the wool over your eyes, making you look one direction while I was tidying up the loose ends of something else.

No, I have not signed James Shields.

The other day, I looked at Justin Verlander's performance in 2014 and found that he allowed a much higher batting average to right-handed hitters than previously in his career. They even dwarfed his 2013 numbers, which were already somewhat inflated by poor infield defense, presumably. While Verlander allowed a higher average on the three pitches he primarily throws to right-handed hitters (he rarely uses the changeup), there was more to this fact than I let on. Let's look back at the numbers.

All of his pitches got worse, but that seems like a huge jump for his slider, right? Well, yes, but the curveball might have actually been a bigger problem. Check out the respective isolated power (ISO) against for each pitch in 2013 and 2014.

*Verlander's changeup ISO also jumped, but we're talking about a double and a triple in a sample of 13 pitches.

As you can see, right-handers teed off on Verlander's curveball in 2014, but also hit fairly well in 2013. Opponents collected 16 hits off of 52 curveballs put in play in 2014, including seven extra base hits. In 2013, opponents had 15 hits in 54 such at-bats, but only two extra base hits.

Instead of looking at Verlander's curveball location -- a relatively futile endeavor, considering righties only put it in play roughly 25 percent of the time -- I want to look at the movement of Verlander's curveball and slider. After struggling with mechanical issues in 2013 and 2014, we should see a decline in movement compared to his Cy Young caliber seasons in 2011 and 2012.

First, a primer: the chart below depicts the average amount of horizontal movement Verlander's slider (red) and curveball (yellow) have had every month over the past four seasons. Higher positive figures indicate more break towards Verlander's glove side, or the left-handed batter's box.

While there is not much change in what his slider does, we see a significant decrease in curveball movement that started in 2013 and continued through 2014.

When assessing vertical movement, both Verlander's slider and curveball showed significant deviations from 2012. In these graphs, lower figures (trending towards the negative) indicate more movement. For reference, the average fastball sits around +9 inches of vertical movement, so the farther away you are from that, the more break you are getting. Verlander's slider didn't move all that much at the start of 2011, but he only threw it eight percent of the time that season. It was at its nastiest in 2012, and has tailed back in 2013 and 2014.

Verlander's curveball isn't quite as easy to assess, but there is a clear drop-off in vertical movement during the 2014 season.

Couple the decline in vertical movement with the decrease in horizontal movement we noted above, and you have a significantly less dangerous curveball. Does this explain the improved numbers for opposing batters? Not necessarily, though the connection would make sense.

★★★

Now that we have uncovered problems with Verlander's fastball, slider, and curveball, it's time to take a look at his mechanics. Thankfully, GWilson already did the dirty work and uncovered that Verlander's release point has changed since his 2011 season. His vertical release point, indicated in the graph below, has gotten higher over the past few years. Additionally, the space between pitch types -- hard, breaking, and offspeed -- is wider than usual. This may mean his pitches are easier for an opposing batter to identify, but that is all guesswork.

Verlander's horizontal release points have also changed, and once again the difference between harder and offspeed pitches has widened.

The differences between his release points in 2013 and 2014 are a bit murky, but there seems to be a bit more volatility with them compared to his 2011 and 2012 seasons. Not only does the average release point jump around more, but the error bars are also wider in some points, indicating more variety in the actual release point locations.

This is the most concrete evidence we have on Justin Verlander's mechanical deficits that have plagued him throughout the past couple seasons. He was able to work through his deficiencies in 2013 and round into shape before September, but the 2014 season was doomed by a number of factors, most of which seem to be stemming from the core muscle repair surgery performed last January.

Will Justin Verlander be back in 2015? Despite all of the research and writing I have done on him in the last week, my guess is still as good as yours. However, with changes in his offseason workout regimen -- he has added 20 pounds of muscle and is already happy with his pitching delivery -- we just might see Justin Verlander return to being Justin Verlander in 2015.