Is Rick Porcello's Sizzling July a Sign of Better Things to Come?

Let's face it: Rick Porcello was really good in the month of July. While we know a 5-0 record and 3.06 ERA don't tell the whole story, they sure do wonders for your GM's confidence in your abilities. While most columnists would stop there, throw in a quote or two and call it a day, readers know that this isn't how we do things around here. Instead, I'm going to take a look at Porcello's July numbers compared to those from the first half of the season and see if we can't figure out what changed with Kid Rick's approach.

First, let's take a look at Porcello's numbers in general.

Like we expected, Porcello's July numbers are miles better than his early seasons stats. His ERA is a full 2 runs lower, and his July FIP and xFIP show that he's right around where he should be. If we're looking forward, xFIP might be the more accurate measure to use because Porcello's home run rate was extremely low in July (remember that homer he gave up to Maicer Izturis on Friday? Yeah, that was it.). Porcello's K rate jumped up a ton, while his walk rate dipped by over a full free pass per 9 innings. This is a bit worrisome, but it's tough to point at this and scream "Unsustainable!!!11!" without a little more context.

The most important stat, in my opinion? Innings per start. Porcello was able to go nearly a full inning deeper into games in July. The numbers in the table above were rounded to the closest 1/3 inning, so the gap is even further than a simple decimal place allows me to show. Getting more out of Porcello is key if the Tigers are going to avoid their abysmal middle relief corps and win ball games going forward.

Next, let's look at how Porcello got some of these numbers.

Note: I excluded Porcello's curveball from the chart because he throws it less than 2% of the time.

When you consider the big jump in Porcello's K-rate in July, seeing a jump in velocity across the board isn't very surprising. His fastballs and changeup, while all slightly faster in July, are still achieving similar results in terms of how often they are in the strike zone, put in play vs. fouled off, etc. What Tigers fans should be encouraged with is the big jump in Porcello's usage of his slider, and what this increased usage represents.

(both charts via pitchfx.texasleaguers.com)

The top chart is the location of Porcello's slider for April-June of this season, while the bottom chart is his slider location in July. As you can see, Kid Rick was much better about keeping his slider down in the zone in July. He actually got fewer swings and misses on the slider in July (8.1%, down from 12.9% in the first half), but hitters put it in play a lot less (16.3%, down from 23.6%). In short, Porcello is throwing his slider more often, hitting the zone more often (62.2%, up from 61.3%), and hitters are fouling it off more (20.7%, up from 12.0%) as opposed to putting it in play. This doesn't explain the whole story, but it paints a big picture as to why he's had more success.

As for the rest of Porcello's improvement (because the slider isn't the only reason for such a huge jump), it's hard to pinpoint based on statistics alone. My original theory was that Porcello would get more movement on his pitches as the season progresses, but would see a drop in velocity to match this increased movement. As we saw above and now see below, this clearly isn't the case.

(both charts via pitchfx.texasleaguers.com)

Other than some slight variation in the slider and changeup in July, Porcello's movement has been about the same as it was earlier in the season. Are those small changes enough to cause the huge difference in numbers we've been examining? Not in the slightest.

So what can we expect from Porcello going forward? Well, we're still not sure. A quick look at his July schedule is a bit of a buzzkill: Kansas City was the only offense he faced that ranks in the top half of the MLB in batting average, on-base percentage, slugging percentage, OPS, or runs scored. Yes, that said "or." Not to mention, his start against the Royals on July 8th was his worst of the month. A July schedule of San Francisco, Kansas City Oakland, Minnesota and the Angels isn't exactly the same as facing the 1927 Yankees five times in a row.

Still, does this mean that we throw everything out the door because Porcello was facing the dregs of the MLB? Not at all. Rick improved substantially in the 2nd half of both the 2009 and 2010 seasons, and I don't think it's any coincidence that he's pointing towards the same trend in 2011.

Stats for this post came from a combination of Baseball-Reference, Fangraphs, and Texas Leaguers.