Prior a definite two-year stud

In the terminology of pitching biomechanics, Mark Prior is a freak.

Stand near Prior in the Cubs' clubhouse, and you'll see that his calves are roughly the size of an average man's thigh. As Prior goes through his delivery and pushes off the rubber, the strong muscles drive his body forward. While the gyrations of a windup like Dontrelle Willis or Hideo Nomo make it difficult to assess their mechanics and add to the deception a hitter faces, Prior's efficient delivery disguises the linear driveline his pitches come through.

While we all know that the quickest path between two points is a straight line, few pitchers can regularly bring a baseball in a straight line to home plate. Prior can.

According to Gary Heil of the National Pitching Alliance, Prior was tested using high-tech Matrix-like technology to assess his mechanics.

"No one else was even close," Heil said. "He's the model; he's perfect."

Dr. Mike Marshall is a former Cy Young Award winner who has completed extensive scientific studies of the pitching motion. Using basic, Newtonian principles of inertia and reaction, Marshall's teachings show that Prior's controlled delivery is near ideal.

He'd be the Six Million Dollar Bionic Pitcher. Except that when his salary arbitration payday comes up, he'll undoubtedly make a lot more than that.

But Prior isn't the only pitcher to achieve such success, and receive so much attention, so early in his career. We consulted with our BP colleagues to create a top 10 list of the best two-year debuts by starting pitchers in the modern era. The factors we evaluated, in rough order of priority, were the following: ERA relative to league average (ERA+), wins above replacement level (WARP), strikeout-to-walk ratio, W-L record, and age at time of debut (younger debuts are considered more impressive). We tried not to consider how the pitcher fared down the road, accounting only for the strength of the first two full seasons (50 or more IP) on their own merits.

10. Wes Ferrell, 1929-1930 Indians
Any number of candidates could have fit in this spot, but Ferrell gets the nod by virtue of winning 20 games in each of his first two seasons, and by pitching better than his unadjusted ERA suggests in a time of hugely inflated offense. He went on to have a solid, consistent career that included 193 wins, and -- since he was almost as good at bat as he was on the mound -- he hit 38 home runs.

9. Roy Oswalt, 2001-2002 Astros
Oswalt hasn't received the press that Prior has, but his numbers have been just as impressive; Prior edges him out in a tiebreaker only because he was a little bit younger at the time of his debut. Though Oswalt doesn't have Prior's tall stature or his textbook mechanics, making him more of an injury risk, here's hoping that he and Prior will be sweating out pennant races together for many years to come.

8. Mark Prior, 2002-2003 Cubs
This seems about right. Prior's strikeout-to-walk ratio in his first two seasons -- perhaps the most important indicator of future success -- is the best of any pitcher on the list.

7. Fernando Valenzuela, 1981-1982 Dodgers
Valenzuela wasn't just a talented pitcher; he was a phenomenon. He drew huge crowds to his starts both at home and on the road, played a significant role in igniting interest in baseball in Mexico and throughout Latin America, and baffled opposing hitters with his screwball. Fernando earned victories in his first 10 decisions in 1981, became the first rookie ever to win the Cy Young Award, and followed it up with a solid sophomore campaign.

Unfortunately, the combination of being overworked and overweight took a toll on Valenzuela, who exhibited a major drop in effectiveness beginning in 1987. He hung on to pitch for another 10 seasons, floating back and forth between the majors, the minors, and the Mexican League, always entertaining his fans. But Fernandomania, like any craze, was short-lived.

6. Babe Ruth, 1915-1916 Red Sox
He makes this list entirely on his own merits: a 41-20 record as a cherubic southpaw in his first two seasons, an ERA 40 percent better than league average, and a record 29 consecutive scoreless innings in the World Series. The Red Sox might have tried him in the outfield sooner, but when your starting left fielder is Duffy Lewis, you don't mess with that.

5. Vida Blue, 1971-1972 Athletics
The mercurial Blue was the pitching embodiment of the '70s, rising to the top like a shooting star with a mix of fastballs, curveballs, and youthful exuberance. He pitched a no-hitter against the Twins in September 1970, in just his eighth major-league start, beginning of a spectacular run of success. In 1971, his first full season, Blue dominated the American League, posting a 24-8 record, a 1.82 ERA, and 301 strikeouts en route to the MVP Award, all at the age of 21.

But after the rise, inevitably, came the fall. His 1972 campaign was marred by a preseason holdout, rumors of an arm injury and, worst of all, the start of his battle with cocaine. While his composite numbers were strong enough to merit his placement on this list, Blue, like some Studio 54 burnout, was able to recapture the glory of 1971 only in short stretches thereafter.

4. Dutch Leonard, 1913-1914 Red Sox
Zero point nine two. Leonard's 1914 ERA record, which came in just his second season, has withstood the test of time. Leonard's 1914 numbers look like a bit of a fluke in retrospect; he threw a spitter back when the pitch was legal, so perhaps he was hacking up some particularly good saliva that year. But Leonard's strong numbers are enough to merit a placement near the top of the list.

3. Russ Ford, 1910-1911 Yankees
We hadn't heard of him, either. Ford wasn't a spitballer, but a scuffer, toiling in semipro ball until he discovered one day, at age 27, that a baseball and an emery board made for a beautiful couple. Legitimate or not, Ford's results were impressive -- a 1.95 ERA and a 48-17 record over almost 600 innings in his first two big-league seasons. But Ford began to experience arm trouble the following season, and his Yankee career was over by 1913, almost as quickly as it began.

2. Ron Guidry, 1977-1978 Yankees
Guidry reached the majors relatively late; he was 26 by the time his first full season rolled around, a solid 1977 campaign that earned him a couple of great nicknames and a little bit of buzz in the Cy Young balloting. But that was nothing compared to what he'd accomplish in 1978: 25 wins, including 13 consecutive to start the season, a 1.74 ERA, an 18-strikeout game, the victory over the Red Sox in the one-game playoff better remembered for Bucky Dent, and finally, a World Series ring. Gator would win 20+ games two more times during his career, but 1978 produced a lifetime of achievements all by itself.

1. Dwight Gooden, 1984-1985 Mets
It was October of 1985, and Gooden was on top of the world. He had just completed the greatest season by a 20-year-old pitcher in baseball history, lapping the rest of the league in ERA, wins, and strikeouts. His team was on the rise, seemingly on the brink not just of a pennant, but of a dynasty. He was a media darling -- the All-American boy made good -- in the media capital of the Western world. The only question was whether he'd be only as good as Walter Johnson, or entirely and overwhelmingly better ...

As it says in the small print of stock prospectuses, past performance is no guarantee of future results. That is especially true of pitchers. Even assuming that Prior can avoid the tragedies that befell Gooden and Blue, there is no guarantee that he'll avoid arm trouble like the kind that derailed the careers of Ford and Valenzuela. According to our Pitcher Abuse Points system, Prior has been worked more heavily this year than all but four other pitchers.

Let's take one final look at our top 10,along with their statistics in their first two seasons:

That's a good, colorful group of arms, but unless you want to count Ruth, there's not a Hall of Famer among them. For whatever reason, the best pitchers of all time -- guys like Steve Carlton, Tom Seaver, Christy Mathewson -- had considerably quieter starts to their careers, posting promising but not dominating numbers, then ratcheting it up to elite status a couple of years later.

But Prior might be a special case, not because of his numbers, but because of his mechanics.

What does a biomechanist see when Prior takes the mound? There are five major principles of proper delivery that can be summarized as balance, posture, anatomical position, rotation, and release. Prior is textbook with all five.

A proper delivery, biomechanically, is focused on driving the ball linearly from cocked position to catcher's mitt, ideally missing the bat in its travel. Balance seems too simple to be important, but watch any game and you are likely to see a pitcher falling off to either side in his delivery. Prior? Direct, linear and compact. Prior is equally ideal with his posture, keeping his 6-foot-5 frame erect through delivery and using both leg drive and gravity to impart force on the ball as he releases it. His elbows stay level, keeping stress off the rotator cuff.

The deceptively simple combination of fastball, curveball, good command, and good mechanics is enough to make Prior one of the five best pitchers in baseball. He isn't a demonstrative guy on the mound, and there are times when he's cruising along so smoothly that he seems to be on autopilot.

But take a look at a list of pitchers that includes names like Gooden, Blue, Ruth and Valenzuela, and it reminds that is for certain: Mark Prior is human.

You can check out more work from the team of writers of the Baseball Prospectus at baseballprospectus.com.