Few things in baseball look as cool as a big curveball.

The ball seems to drop out of midair and buckle the batter's knees for strike three.

Now that half of the year has passed, and the sample size is pretty large, I thought I'd take a look at who's had the most effective curveball this season.

Checking Fangraphs.com's list of pitchers sorted by curveball effectiveness, I was surprised to see my favorite pitcher, Dallas Braden, in first place.

He doesn't even throw a curveball.

The pitch f/x algorithm says Braden throws a curve 0.3 percent of the time, at roughly the same speed as his slider.

I've seen Braden pitch. He throws a slow slider with big, looping break. It looks sort of like a curve when he throws it right.

What's most likely happening is that a few of Braden's biggest-breaking sliders are getting classified as curves. That would explain the effectiveness, as a pitch with slider velocity and curveball break would be very tough to hit.

So we can write Braden's curve off as just his best slider.

Second place on the list belongs to Brad Bergesen of the Orioles. It's pretty much the same story with him, as his "curve," which he apparently throws just 3.3 percent of the time, is slightly slower than his slider.

I've read a few scouting reports on Bergesen. They all mention a fastball, a change, and a slider. None mention a curve. Plus, he throws from a pretty low arm angle, to the point where it would be difficult to stay on top of a curve.

Third place on the list, however, belongs to a pitcher with a curveball.

And that pitcher, of all people, is Livan Hernandez.

I'm not sure which is harder to believe: that Hernandez has the best curve in the majors or that Tim Wakefield has the best fastball in the majors.

Yet the data show both are true.

At least with Wakefield, it's understandable. Hitters go up there looking for the knuckleball, never the fastball, so it confuses them.

But what's the deal with Hernandez?

Livan Hernandez's fastball goes all of 84 mph.

His curveball goes 66.

When he was more of a power pitcher, or at least not a pure finesse guy, Hernandez had a fairly standard low-70s curve, and it was a good pitch.

But in 2006, he started throwing a bigger, slower curve in the mid-60s.

In 2006, the pitch was slightly below average. In 2007, it was slightly above.

Last year, Hernandez cut back his use of it, and it was terrible when he did throw it, rating 2.15 runs below average per 100 pitches. Overall, the pitch cost him 3.9 runs on the season.

This year, it rates a whopping 3.78 runs *above average* and has helped him prevent an extra 3.6 runs on the season.

In practical terms, here's what this means.

Let's say that an average RA (Run Average) is 5.00. Don't sweat that number if it's right or wrong; it's just an example.

Now let's say that every nine innings, a pitcher throws about 125 pitches. Again, don't sweat the number.

With those admittedly rough figures in place, let's look at how Hernandez's curveball rates.

For every 125 curves he threw in 2008, Hernandez allowed about 2.69 extra runs. That means that his 2008 curve basically rates as a 7.69 RA pitch.

For every 125 curves he's thrown in 2009, Hernandez has saved about 4.73 extra runs. That means that his 2009 curve basically rates as a 0.27 RA pitch.

I know that's a gross oversimplification of the numbers, but the point is that the difference is extreme.

I've seen Hernandez's curve before. It's exactly what you would expect it to look like. It's very slow and has some big, looping break.

Just for comparison's sake, here are the eight pitchers who throw curves that average less than 70 mph and the effectiveness of their curves (per 100 pitches):

Tim Wakefield: 59.4 mph, .49 runs below average

Livan Hernandez: 66.3 mph, 3.78 runs above average

Randy Wolf: 67.0 mph, 1.67 runs above average

Vicente Padilla: 68.1 mph, 1.25 runs below average

Jamie Moyer: 68.7 mph, 1.85 runs above average

Kenshin Kawakami: 69.1 mph, 1.95 runs above average

Doug Davis: 69.1 mph, .55 runs above average

Carlos Zambrano: 69.8 mph, 1.31 runs below average

I find this very interesting. Zambrano's curve is a trick pitch he throws less than one percent of the time, Wakefield is an anomaly because of the knuckleball, and then five of the other six pitchers rate above average with the slow curve, with Hernandez, Wolf, Moyer, and Kawakami in plus-plus pitch territory.

Perhaps seeing a pitch come in below 70 mph just disconcerts a hitter, or maybe the sheer amount of looping break is overwhelming, but whatever the reason, slow curves seem to really baffle hitters.

Regardless of the value of slow curves in general, it's also significant that Hernandez's rates nearly twice as well as the next best curve in the group (Kawakami's). It's also interesting that aside from Wakefield, Hernandez throws the slowest curve in the bunch, and it's actually coming in much harder than 2006-2008, when it was down in the 64-65 range.

Looking at Hernandez's pitch f/x curve velocity chart, we can see more interesting stuff. In 2009, Hernandez's curve has ranged from 60 to 77 mph. To use a rather worn-out baseball term, he "adds and subtracts" from the pitch.

It could be that Hernandez's variation of the speed and break of the curve makes it more difficult to pick up out of his hand and also more difficult to square up with the bat.

Usually a batter, when he recognizes a pitch, can assume some things about it. For example, Hernandez's fastball has a little bit of run in to righties and away from lefties, and it's always 82-87 mph.

However, with a 17-mph speed range (and inversely correlated break range, obviously) on the curveball, Hernandez doesn't allow batters to assume anything about it. Even if they recognize the pitch, batters must adapt to the speed and movement of the pitch on the fly.

On top of that, Hernandez only uses the curve 6.1 percent of the time, meaning that a specific batter only sees it once or twice a game. Hitters won't be sitting on the curve because he only throws it about once every 13 or 14 pitches, and if a hitter waits for that, there's a good chance he won't get it.

Whatever the reason for its success, Hernandez's curveball has been the most effective of any curveball in the majors this year, and it has been a big part of his improvement after three bad seasons.