Part of baseball that we seem to love (and in many cases hate) so much is the unpredictability of pitcher performances. Cliff Lee, who spent a large part of last season pitching in AAA, is currently the American League’s top starting pitcher according to VORP at 37.2 runs. The talented Tim Lincecum, who started the 2007 season in A-ball, currently leads all major league pitchers in VORP at 38.1 runs. Edinson Volquez, who struggled to turn his immense talent into results with the Texas Rangers organization for five seasons, has now emerged as one of the National League’s dominant arms. Another example of a pitcher putting it all together to establish himself as an incredibly effective pitcher in 2008 is White Sox starter John Danks.

Acquired in the deal that sent Brandon McCarthy to the Rangers, Danks made his major league debut for the White Sox last year in his age 22 season experiencing more than a few growing pains as the season progressed. So-so control, coupled with extreme flyball tendencies made Danks’ first major league season a rather forgettable one. At the end of the year he had pitched 139 innings, posting an ERA of 5.50 and a VORP of just 1.8 runs.

This season, we have seen an entirely different pitcher: Danks has already pitched 107 innings, posting a 2.52 ERA and a VORP of 34.8 runs, the final figure currently being the second best mark in the American League.

What has caused such an unprecedented turnaround? Sure Danks has always been talented, but an ERA drop of nearly three full runs indicates he has been utilizing that talent differently than he did last season. Let’s take a look at Danks from a Pitch F/X standpoint. I’ll be the first to admit, I have only experimented with the tool a handful of times, so please feel free to drop a comment if you have a suggestion.

Let’s first take a look at Danks peripherals and batted ball data over the past two seasons:

Looking at his peripherals and batted ball numbers alone, there is no reason why Danks shouldn’t be pitching better this year. While there are clear improvements in both his strikeout and walk rates, the difference maker for him this year has been the nearly 12% increase in his groundball percentage which has led to significantly less flyballs leaving the ballpark. There is nearly a .25 difference between his BABIP and eBABIP meaning he may be a little hit-lucky this season, but make no mistake, his peripherals have taken a major step forward in the right direction this year.

Now for the fun stuff, here’s a look at Danks from a Pitch F/X perspective. First, the movement of his pitches during the 2007 season:

via baseball.bornbybits.com

And now, the movement of his pitches during the 2008 season.

via baseball.bornbybits.com

The addition of a fourth pitch might be the precise reason as to why John Danks has made such a leap forward in 2008.

Before the season began, Danks was essentially a three pitch pitcher throwing a heater, a breaking ball and a changeup.

This season, he added a cut fastball to his repertoire and it’s a pitch he’s used with great frequency throwing it nearly 22% of the time on the mound. This, of course, has allowed Danks to use his other pitches, particularly his fastball, with a little less frequency. Last season Danks threw his heater to hitters a little over 60% of the time. This season, he’s throwing his fastball just 46% of the time. Perhaps more revealing of the trust he placed in his fastball was the way he used it in potential strikeout counts. In 0-2, 1-2, 2-2, and 3-2 counts during the 2007 season, he used his fastball nearly 70%, 44%, 41% and 48% of the time respectively. This season, he has used his fastball nearly 50%, 35%, 33% and 48% of the time in those same counts. This should come as no surprise: When a pitcher adds another pitch to his repertoire, he’s going to use his already existing pitches a bit less, but my personal belief if that Danks tried to use what was an average heater as an out pitch a bit too much which led to far too many balls in play and gaudy home run totals. Pure speculation on my part, but the addition of that cutter has allowed him to utilize his fastball with a bit more selectively.

From a pure stuff, standpoint, Danks has made plenty of improvements from his rookie year. His average fastball velocity is 92.16 MPH, a near two MPH improvement from 2007 when he was throwing his heater for an average velocity of 90.97 MPH. He also may be pitching more aggressively with his fastball. He’s getting a little less horizontal break with his fastball, but he’s getting the ball up a little more vertically, meaning he’s not afraid to challenge hitters with his heater and induce them to chase to the pitch up.

He’s also made changes with his breaking ball. The 2007 Pitch F/X tool, classified Danks’ breaking ball as a slider, but this season, it is classified as a curveball. Whatever you want to call it, the breaking ball is being thrown with nearly the same velocity, however, it’s getting a little more vertical break down in the zone (-1.33 in. as opposed to -0.92 in.) and significantly more late horizontal break (-3.5 in. as opposed to -1.97 in.). Simply put, his breaking ball is a bit sharper than it was last season despite nearly identical velocities.

The addition of a cut fastball has helped Danks against left-handed hitters significantly. Last season, lefties torched Danks to a .281/.362/.521 line with seven home runs in 121 AB’s. This season lefties are hitting just .264/.317/.327 against him with one home run in 110 AB’s. Versus lefties, Danks is throwing his cutter 33.53% of the time, his heater being the only pitch he uses more frequently against them.

His change is his bread and butter pitcher against right-handed hitters. This shouldn’t come as much of a surprise, many left-handed pitchers use their changeup primarily against right-handed hitters, but this season Danks is getting nearly two more inches of horizontal break on the pitch. He’s thrown the pitch to right-handed hitters 26.76% of the time they’re in the box, as opposed to 8.61% of the time lefties are in the box. With a near 10 MPH differential between his heater and his changeup, he’s kept plenty of right-handed hitters off balance this year.

All in all Danks has improved just about every facet of his game. During the 2007 season he may have relied far too heavily on his fastball, but the addition of a cutter this season is making hitters guess a little more. Add that to improved control, a little more velocity to his fastball and enhanced groundball tendencies and an unpredictable turnaround is well...quite predictable.