I thought it would be an interesting idea to see who has the most effective curves in the major leagues this year.
I'm measuring curve effectiveness by Pitch Type Linear Weights, which says how many runs a pitcher prevents above average every time he throws 100 pitches.
So, if I say a curve's effectiveness is +1 run, that means that every 100 curves that pitcher throws, he allows one run less than average.
I set two groundrules for this. First of all, pitchers have to have thrown at least 30 innings this year. Second, they have to use the curve at least 10 percent of the time.
For each pitcher, I'll list the average curve velocity, average curve movement relative to an average major league fastball (if you want to know why I'm comparing it to a fastball, just ask), curve usage (how often the pitcher throws the curve), and curve effectiveness (as measured by Pitch Type Linear Weights).
Let's take a look.
Curve Velocity: 77.7 mph
Curve Break: 12.6 inches right to left, 9.3 inches down
Curve Usage: 23.0%
Curve Effectiveness: 2.76 runs above average
Hunter's success this season has come largely thanks to his curve, a power breaker with a lot of lateral movement. While Hunter has been criticized for often losing feel for the pitch, he's done a much better job keeping the break on his curve consistent in 2009.
Curve Velocity: 78.7 mph
Curve Break: 11.2 inches left to right, 18.4 inches down
Curve Usage: 27.6%
Curve Effectiveness: 2.95 runs above average
The Athletics' young left hander has struggled mightily with his fastball and change up this season, but his curveball has been phenomenal.
Gonzalez's curve combines good velocity and excellent movement; few curveballs have more "drop" than his.
If Gonzalez improves his command, his curve could become the most effective in the majors.
Curve Velocity: 79.9 mph
Curve Break: 13.3 inches right to left, 14.1 inches down
Curve Usage: 19.5%
Curve Effectiveness: 3.00 runs above average
Like Gonzalez, Floyd was always touted as one of the best curveball prospects when he was coming up, and has seen the pitch excel in the majors. He's added some velocity to it this year, which has really helped the pitch become much more effective.
Curve Velocity: 72.9 mph
Curve Break: 10.8 inches left to right, 19.1 inches down
Curve Usage: 16.1%
Curve Effectiveness: 3.13 runs above average
It probably doesn't surprise you that Zito's had the most effective lefty curve in the majors this season.
It probably does surprise you that it's having by far its best season.
Zito's curve had never registered more than 1.02 runs above average in any year prior to this one. In his Cy Young 2002 season, it was just .80 runs above average.
That doesn't mean it wasn't a great pitch then. What it means is that Zito threw it so much that batters always looked for it instead of his other pitches. That meant that they did a decent job against the curve, but his other pitches, while not impressive on their own, often snuck by hitters.
Zito's cut back on his curve usage some (he used to throw it 22-27% of the time), so batters can't afford to look for it anymore. That means that the pitch's staggering break actually surprises hitters in 2009, making it the super-effective pitch it's always been made out to be.
Zito also has thrown the curve harder than ever this year; it was 1-2 mph slower in years past. He hasn't sacrificed any break for the extra velocity, so that's helped as well.
Curve Velocity: 74.1 mph
Curve Break: 13.5 inches right to left, 18.0 inches down
Curve Usage: 21.5%
Curve Effectiveness: 3.28 runs above average
Wainwright is another example of the stats backing up the scouts. His curveball is considered one of the best in the game, and that certainly appears to be true.
Like Zito, Wainwright throws a softer, bigger curve than Hunter, Gonzalez, or Floyd. The slow breaker headlines an exceptional group of offspeed pitches for the Cardinals righty.
Curve Velocity: 76.7 mph
Curve Break: 13.0 inches right to left, 15.5 inches down
Curve Usage: 13.8%
Curve Effectiveness: 3.36 runs above average
One of the most surprising entries on this list, Hammel used to throw a bigger, softer curve with Tampa Bay, but exchanged it for a faster, shorter version with Colorado. The Tampa Bay version was just an average pitch, but in Colorado, the curve has taken off.
The curve is the main reason Hammel has matured into a nice #4 starter this season.
Curve Velocity: 75.8 mph
Curve Break: 8.7 inches right to left, 12.3 inches down
Curve Usage: 11.5%
Curve Effectiveness: 3.48 runs above average
Reyes' curve is neither fast nor big, but it's gotten exceptional results this season. He's really cut back his usage from 2007-08, so hitters may not be looking for the pitch.
Curve Velocity: 72.6 mph
Curve Break: 13.4 inches right to left, 14.1 inches down
Curve Usage: 16.7%
Curve Effectiveness: 3.54 runs above average
While many other pitchers on this list have seen benefits as a result from throwing their curves harder and less often, Vazquez has done the opposite.
He typically threw a 74-76 mph curveball about 10-12% of the time prior to 2009, but this season, he's thrown the pitch slower and more frequently, and has gotten much more success.
While Vazquez's curve doesn't have the raw movement of, say, Zito's, it breaks very late, and he locates the pitch well. As the numbers attest, it's devastating when it's on.
Curve Velocity: 78.6 mph
Curve Break: 14.6 inches right to left, 15.2 inches down
Curve Usage: 21.6%
Curve Effectiveness: 3.56 runs above average
Perhaps the most surprising inclusion on this list is Wright, a journeyman reliever struggling in Kansas City.
While his fastball and cutter have gotten hammered this year, Wright's curveball has been exceptional, fooling hitters with a great amount of lateral break away from right handers.
Like Vazquez, Wright has used the pitch more than ever this season. He also has added some velocity to the pitch without sacrificing break.
Hitters are sitting on Wright's fastballs, because he throws them 73% of the time, but they seem to be caught off-guard by the curveball.
Curve Velocity: 77.1 mph
Curve Break: 11.8 inches right to left, 15 inches down
Curve Usage: 19.9%
Curve Effectiveness: 3.76 runs above average
Franklin throws seemingly every pitch known to man (four-seam fastball, two-seam fastball, cutter, slider, curve, changeup, splitter, knuckleball), and the curve isn't even his most effective pitch (that would be the splitter, 4.84 runs above average).
Because Franklin throws so many different pitches, hitters don't know what to expect, making the fastest and slowest pitches in his arsenal that much more dangerous.
While Franklin's curve isn't exceptional in any one aspect, his style of pitching makes it difficult to predict, and that deception has propelled it to be the most effective regularly-thrown curveball in the major leagues.