Pitchers with premium velocity have an advantage because their heat gives themselves a bit more margin for error. A quicker fastball has a better chance of missing bats, keeping the ball out of play and leading to more strikeouts. The faster the pitch, the less time the hitter has to react, and being off by a fraction of a second can be the difference between a hit and weak contact or a strikeout.

The harder a pitcher throws, the more likely he is to have a lower ERA, and that effect might be even more pronounced in the postseason.

Of course, velocity isn’t everything for a pitcher. A pitcher’s breaking ball, other offspeed pitches, delivery, arm action, control, athleticism, pitchability and health are among the myriad factors that affect his future. In fact, velocity isn’t even everything when it comes to the fastball alone. Movement, such as whether the pitch tails, bores or sinks, is important, and the ability to command the fastball has separated plenty of successful major leaguers from pitching prospect flameouts.

But let’s face it: fastball velocity matters—and it’s simple to quantify. The Prospect Handbook offers 469 scouting reports on pitching prospects, with information on what pitches they throw and how hard they throw their fastballs.

A Look Back

But before we look at the hardest throwers from 2007, let’s take a look back at the highest peak velocity readings from the 2002 Prospect Handbook, along with those pitchers’ career major league numbers. Ages are as of Sept. 1, 2001, and an asterisk (*) denotes lefthanded pitcher.

To review, Carlos Zambrano has been one of the best pitchers in baseball for the last five seasons. Aaron Cook has been an above-average starter, despite pitching his home games at Coors Field. Francisco Rodriguez and Brad Lidge converted to relievers before they reached the majors, and both were two of the elite closers in baseball at their best. Bobby Jenks has also emerged as one of baseball’s best relievers. Brandon League doesn’t have too many major league innings under his belt—mostly because of shoulder and oblique issues in 2007—but he shows the potential to be a serviceable reliever when healthy.

After that, the talent drops off. Erick Threets, Seth McClung and Ben Howard all made the major leagues but haven’t panned out, mostly due to a lack of quality secondary offerings or poor command. (Threets in fact is in this year’s Giants Top 30, one more time.) Sean Henn had Tommy John surgery after the 2001 season and never regained premium velocity. Anthony Pluta had poor command and never made it out of high Class A. Nick Neugebauer was one of baseball’s best pitching prospects after he dominated Double-A and Triple-A in 2001, but arm injuries destroyed his career.

So out of 13 fireballers, the list yields five above-average pitchers—including one of the game’s best pitchers—and an unfinished product in League. All in all, it’s a solid list given that the only criterion is peak fastball velocity. But it also shows that lighting up the radar gun isn’t everything in pitching prospect evaluation.

Back To The Present

Even the fastball, the pitch that’s the easiest to quantify, has its own margin for error. While reports vary from scout to scout and from gun to gun (and stadium guns notorious for inflating the readings fans see), the Prospect Handbook presents the most accurate velocity readings and reports you will find on pitching prospects.

The following is a list of the top 10 peak velocities recorded by pitchers in the Prospect Handbook. Relief pitchers have been excluded from the list (but will be touched on later) because of the natural advantage they have of being able to throw at maximum velocity in shorter stints.

Of course, with a 13-way tie for tenth, the list really goes 23 deep. As always, an asterisk (*) denotes a lefthander, and a pound sign (#) signifies that a pitcher missed either most or all of the 2007 season due to injury or will miss the 2008 season. Statistics are aggregate minor league totals from the 2007 season, and ages are as of Sept. 1, 2007.

Many of the game’s elite pitching prospects are here, like Joba Chamberlain, Clayton Kershaw, Jake McGee and Franklin Morales. Others are mainly getting by with an overpowering fastball and still refining their secondary pitches. Wilmer Font is the most unrefined pitcher here, but at 17 he already is touching 98 mph.

On the whole, these pitchers don’t have the best command. Among pitchers in full-season ball, only Chamberlain, Jeff Samardzija and Ryan Tucker had a walks per nine innings rate lower than 3.0, and Tucker barely snuck in with a 2.99 BB/9. Samardzija is an interesting case because of a rare convergence of low strikeout rate and high-90s fastball. Blue Jays fans will remember Brandon League had a similar profile.

At 23, Felipe Paulino and Max Scherzer are the oldest players here; Paulino’s 102 is reported by other organizations’ scouts, while the Astros say he’s peaked at 100. The list tends to skew young, though, with an average age of 20.4 years old. That’s partly a byproduct of who is eligible for the Handbook, but it’s also because of pitchers’ aging patterns. Pitchers gain velocity as they fill out their frames and improve their mechanics, but over time many of them lose velocity as quickly as their early 20s due to injuries, workload or regular wear and tear.

Many of these players will likely one day find their way into a major league bullpen, where their plus-plus velocity will play up. Scherzer and Daniel Bard, for example, already have been discussed as potential relievers.

Risky Business

Among the injured hurlers, Erik Cordier didn’t pitch last season after having Tommy John surgery, the second time he has missed a full season because of injury. Cordier missed all of 2005 following knee surgery. Mark Rogers had shoulder surgery that cost him all of his 2007 season. Brad Lincoln was the fourth overall pick in the 2006 draft and missed all of last season after having TJ.

Andrew Brackman, the Yankees’ first-round pick last June, touched 100 mph at North Carolina State. He won’t pitch again until 2009. Craig Italiano made six starts before a line drive off the head left him with a skull fracture. That makes two lost seasons in a row for Italiano, as he lost all but four games in 2006 to labrum surgery on his shoulder.

Check back later for a look at the hardest-throwing relief prospects as well as a look at the full list of lefthanded flamethrowers.