Every major league pitcher has an out-pitch -- the weapon of choice when it's time to put a hitter away. It's just that some are better -- sometimes, much better -- than others. That's what separates the great pitchers from the merely average.
An ordinary 88-mph fastball isn't going to do the job -- unless it features extraordinary movement. Often, an out-pitch is a breaking pitch or off-speed pitch, which makes recognition tougher while disrupting timing.
The good ones can't be hit even when a hitter is expecting its arrival. But the best ones are often part of a complete package -- the more different looks a pitcher can present, the tougher it is to handle the signature pitch.
We surveyed scouts, managers and general managers in compiling a list of the game's 10 best.
1) Mariano Rivera's cut fastball:
A few years ago, when Rivera was unquestionably in his prime, this was arguably the Toughest Pitch in Baseball. Rivera broke more bats with this than any pitcher in the game.
Now, Rivera is older and there are more clicks on his pitching odometer. But still, this is a dominant pitch thrown by a dominant closer.
"It's such a hard pitch to recognize,'' says Jim Kaat, former pitcher and current Yankees broadcaster. "Left-handed hitters know it's coming and it still doesn't help. If you cheat and try to get out front, you pull it. And if you wait on it, it ties you up inside. It's just the perfect pitch.''
2) Kerry Wood's curveball:
Like Nolan Ryan, the Texas gunslinger whom Wood emulates, the combination of a 95-mph fastball and a hard-breaking curveball presents a lethal combination.
Not many pitchers throw an over-the-top curve anymore, as the slider has become the breaking pitch of preference. But Wood not only has the 12-to-6 break, he also throws it nearly as hard as some lesser pitchers throw their fastball.
"That hard, sharp break is filthy,'' says one major league manager.
3) John Smoltz' slider:
When Smoltz was a starter, he varied his repertoire more, pacing himself for a 100-pitch outing. Now that he operates exclusively out of the bullpen as Atlanta's closer, he doesn't have to pace himself or worry about overexposing his signature pitch.
If Smoltz is in the game, it means the opponents are trailing. Thanks to this wicked slider, which darts across the strike zone, it's doubtful the Braves' lead is going to be squandered.
4) Eric Gagne's changeup:
Like fellow All-Star closers Keith Foulke and Trevor Hoffman, Gagne's best pitch is this off-speed choice which can upset a hitter's timing. Unlike Foulke and Hoffman, Gagne has a fastball that tops out in the mid- to high-90s, and the contrast between the two makes each that much more effective.
"It really is the old 'Bugs Bunny' change,'' says an advance scout. "You can swing at it three times and still not hit it.''
5) Roger Clemens' split-finger fastball:
A few years ago, in a postseason interview session, Clemens famously -- and comically -- referred to "Mr. Splittee,'' his nickname for his devastating, darting fastball.
Catching up with Clemens' four-seamer is a challenge in and of itself. But when he mixes in this, often in the dirt, hitters can look awfully foolish as they go fishing.
"The guy's a physical marvel,'' one baseball executive says. "He may have lost a little velocity on his hard stuff, but not much.''
6) Tim Wakefield's knuckleball:
When Wakefield's signature pitch flattens, it's an inviting target and easier to hit than a batting practice fastball. Just ask Aaron Boone.
But when the conditions are right and the knuckler is moving, there's no more confounding pitch in the game. Go ahead -- try to hit a butterfly with your bat.
The knuckler has all but disappeared from the game -- Steve Sparks still mixes one in and Mike Mussina toys with a knuckle-curve -- meaning hitters only to get see it a few times per season. For many, that's plenty.
7) Billy Wagner's four-seam fastball:
This pitch defies the laws of physics. Actually, Wagner defies the laws of physics.
"You see him,'' says Red Sox GM Theo Epstein, "and you wonder: how does that pitch come from that body.''
Wagner's listed height and weight -- 5-foot-11, 195 pounds -- seems preposterous. He seems an inch or two shorter and a good 20 pounds lighter than that. But somehow -- good genes, arm speed -- he delivers, often registering 100 mph on radar guns.
Sure, velocity may be overrated. But not in this case.
"No one ever gets comfortable against him,'' adds a scout.
8) Barry Zito's curveball:
Zito's curveball is the perfect West Coast pitch, as it befits the hurler himself -- mellow and relaxed.
While Wood's curveball is sharp and powerful, Zito's deuce is soft and gradual. It freezes hitters as it ever-so-gradually rolls from top to bottom, as if delivered to the plate on a cloud.
9) Kevin Brown's sinker:
Brown is older now and has a variety of physical problems -- seven trips to the disabled list since 2000 -- have reduced his durability. But healthy, as he seems to be this season for the Yankees, he still has this devastating power sinker.
Try as they might to lay off it, hitters can't help but pound the ball into the ground, making for a busy night for his infielders, but a long, frustrating night for the opponent.
"That thing is so heavy and explosive -- it's like lead,'' marvels one GM.
10) Jim Mecir's screwball:
The screw ball is something of a baseball dinosaur, nearing extinction on the mound. Fernando Valenzuela's signature pitch in the 1980s, it's slowly disappeared in the last decade. Only a handful of pitchers -- including John Franco -- throw it with any degree of regularity.
Though right-handed, Mecir's scroogie has almost turned him into a situational lefty since the pitch eats up left-handed hitters. Unfortunately for Mecir, right-handed hitters don't have nearly as much trouble with it.
Sean McAdam of the Providence (R.I.) Journal covers baseball for ESPN.com.