What went wrong with Justin Verlander in 2014?

Justin Verlander struggled through one of the worst seasons of his career in 2014, ending the year with a 4.54 ERA and 1.40 WHIP in 206 innings. All of those statistics were his worst totals since 2008, a season that all Tigers fans would like to forget. Verlander was still a valuable contributor, with over 200 innings pitched and 3.3 WAR for his eighth consecutive season. However, he was far from the tour de force we saw in 2011 and 2012, and a fair shake worse than in 2013.

As such, asking "what went wrong?" is a bit of a loaded question. In short, a lot of things went wrong. He gave up the most hits of any season in his career. He had his lowest strikeout total since his rookie season. His fastball velocity dropped. All of these things, along with a few others, contributed to his poor numbers. Many of them appear to be a consequence of his core muscle repair surgery from the previous offseason.

We stepped back to take a broad look at Verlander last week, and now I want to point out how he deviated from the plan in 2014. Later this week, we will explore some specific facets of the game that Verlander struggled with, and hopefully find things that he can improve upon in 2015 -- you know, besides "not being hurt."

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The first thing that jumps out about Verlander's 2014 numbers is how much better opponents performed against him. In his career, Verlander has allowed a .239 batting average and .366 slugging average. In 2014, those figures jumped to .275 and .426, respectively. The batting average jump is to be expected, but the boost in power that opponents had was startling. While Verlander did not give up an exorbitant amount of home runs -- his 18 dingers allowed were actually his lowest total since 2010 -- he gave up a whopping 51 doubles. In all, his 8.7 extra base hit rate was well above his career rate of 6.9 percent. Or, if you prefer, his isolated power (ISO) allowed jumped from .127 to .151. Regardless of your preferred metric, opponents hit Verlander harder in 2014.

The power didn't come from where you would think, either. Left-handed batters hit .239/.308/.378 off Verlander last season, not much better than the .232/.299/.362 line he has allowed in his career. Right-handed hitters teed off on Verlander, though, hitting .321/.361/.489 with 40 extra base hits in 378 plate appearances. Righties had a .365 BABIP against Verlander, but his .168 ISO allowed indicates that "luck" is not the reason for their success.

Another reason why luck may not be the culprit? This is the second year in a row that Verlander has struggled against right-handed hitters. Righties hit .275/.327/.412 off him last season, much better than the .248/.304/.371 line he has allowed in his career. His .137 ISO allowed in 2013 pales to what happened last season, but the high batting average and high BABIP (.330) were still around.

However, there were some fundamental differences between the two seasons. In 2013, Verlander allowed 11 of his 19 home runs to right-handed hitters. His home run per fly ball rate against righties was nearly double what it was against lefties. He allowed just 23 total extra base hits against righties in 2013, a 6.1 percent rate in line with his career averages. The bump in batting average and BABIP can be partially explained by the defense, particularly on the left side of the infield. Nearly all of the ground ball singles Verlander allowed went between Jhonny Peralta and Miguel Cabrera, resulting in a season-long BABIP of .290 on ground balls, 45 points higher than the league split of .245.

What happened between 2013 and 2014? Verlander's mix of pitches against right-handed batters went virtually unchanged, save for a couple of percentage points here and there. He threw roughly 55 percent fastballs, 28-30 percent sliders, 12-14 percent curveballs, and the occasional changeup.

There doesn't seem to be a smoking gun here, though. Opposing righties hit better against all four of Verlander's pitches in 2014 compared to 2013, and it wasn't particularly close (except for changeups, which a whopping three batters put into play in 2013).

Right-handed batters created a lot of problems for Verlander in 2014, but left-handers also played a role in his struggles. Verlander had a pedestrian 2.24 strikeout-to-walk ratio against lefties, in large part thanks to a walk rate of 8.7 percent. Both righties and lefties showed more discipline against him last season, but lefties swung at just 27 percent of pitches that he threw outside the strike zone (O-swing percentage). Verlander's career O-swing percentage is around 30 percent, but he was at 33 percent or higher from 2011 to 2013, so the drop to 27 percent is even farther than a simple glance at Fangraphs' tables suggests.

Ironically, Verlander's problem may have been that he actually caught too much of the plate against lefties. Here is his average pitch location to left-handed hitters in 2013, with a healthy distribution right along the outside half.

In 2014, the deepest red zone started to drift a bit more into the middle of the plate.

A higher percentage of pitches in the middle of the plate coupled with a higher percentage of pitches nowhere near the strike zone is not a recipe for success, and it's a bit surprising that Verlander wasn't worse against left-handers in 2014.

These are not the only things that went wrong for Justin Verlander in 2014, but they are some of the most apparent with the data we have available. Verlander struggled against right-handers more than lefties for some apparent reason, but struggled to locate his pitches against left-handers more than righties, resulting in a higher walk rate. His troubles against righties don't seem entirely BABIP-related, but could potentially be a blip on the radar as he distances himself further from his core muscle repair surgery in January of 2014.