Editor's Note: This story appears in the April 9 edition of ESPN The Magazine.
Baseball is built on five tools: hitting for average, hitting for power, throwing, fielding and running. Here's a look at the players whose skills, or lack thereof, in each area could make or break their teams. Plus, to wrap everything up, there's a sixth category -- chemistry -- on the guys who have a sixth sense for creating it.
Joe Mauer, C, Twins
OK, so you were the best hitter in the AL last year, at age 23. And you play the most physically and mentally demanding position on the field. But what have you done for us lately? The Twins got career years from Justin Morneau, Torii Hunter and Michael Cuddyer. That won't happen again, so they need even more from Mauer.
Howie Kendrick, 2B, Angels
He doesn't have great power or speed, but this 23-year-old was one of the best pure hitters in the minors. The Angels desperately need him to hit like that in the majors, because after missing out on key free agents and trades, this team is starting to feel ordinary. Kendrick could change the Angels' entire perspective on themselves.
Adam Dunn, LF, Reds
One of the most complex hitters in baseball, Dunn led the NL in K's, was second in walks and hit the seventh most home runs in 2006, yet he batted only .234. Of his 194 K's, 46 were called. If he focused on contact, he could hit 50 homers and drive in 150. Dunn has 12 sacrifice flies in five full seasons; Justin Morneau had 11 last year.
Alex Rodriguez, 3B, Yankees
He can't seem to find love or happiness in the Bronx. He was MVP in '05 but hasn't "earned his pinstripes" due to playoff failures. He was Player of the Month last May; by June 5 he was getting booed. A-Rod needs to hit homers, lots of 'em, every month, especially October. It's the one way he can distinguish himself from Derek Jeter.
Adam LaRoche, 1B, Pirates
In addition to the 30-plus dingers LaRoche will hit, the Bucs benefit from the residual impact he'll have on their best player. Jason Bay has put up great numbers without lineup protection the past two years, and now opponents can't pitch around him with LaRoche's big bat behind him. We'll finally find out just how good Bay can be.
Scott Rolen, 3B, Cardinals
The champs can't rely on "all Albert, all the time" this season because they don't have enough pitching. On many days they'll need to outslug opponents. That means Rolen, who hit just eight homers after the break due to his balky shoulder, has to give the Cards more power if they're going to repeat even as NL Central champs.
Ben Sheets, RHP, Brewers
In 2004 he showed the power of Clemens and the command of Maddux, fanning 264 and walking 32 in 237 IPs. Now Sheets is working his way back from injuries, and control is usually last to come. But he K'd 45 in September and walked just four. He's the difference between the Brew Crew winning the NL Central and finishing fourth.
Joel Pineiro, RHP, Red Sox
With major money invested in the rotation, the Red Sox signed failed starter Piñeiro to close. They thought his fastball would have more life in short stints, but his spring work didn't inspire, so Jonathan Papelbon went back to the pen. With Mike Timlin opening on the DL (oblique), the Sox now need Piñeiro for vital setup help.
Scott Olsen, LHP, Marlins
Organizations try to protect young arms from big jumps in innings, but when you have an entire staff of kids, like the '06 Marlins did, you can't protect them all. Aníbal Sánchez and Josh Johnson are already hurting, so Florida needs another workhorse to take the load off Dontrelle Willis. The fiery Olsen could emerge as an ace.
Carlos Beltran, CF, Mets
Andruw Jones owns many more Gold Gloves, but Beltrán's defense is far more important to the Mets than Jones' is to the Braves. Why? Beltrán plays between Moisés Alou and Shawn Green. At this point, their range is a step and a dive. The patch of grass Beltrán has to cover is much bigger than any other centerfielder's.
Victor Martinez, C, Indians
With his 18 percent rate in throwing out runners, teams will send everyone. His improvement is critical because at the start of every game, Martínez gives the Indians a major offensive advantage at catcher. He projects at .300/20/95, which would make him the top AL catcher but only about the seventh most productive first baseman.
A lasting memory from the 2006 Series is of Tigers pitchers throwing wildly to first and third bases. As isolated incidents, the errors aren't a big deal. In the Series they were huge, like Tony Romo's dropping the snap in the NFL playoffs. We'll know the Tigers are over it only when the pitchers make several plays after an error.
Carl Crawford, LF, Devil Rays
There was talk in Rays camp of batting Crawford second and Delmon Young third. Young walked only once in 126 ABs in '06 and, according to STATS, swung at 68.7 percent of the pitches he saw, the highest percentage in a decade. That's like giving Crawford, just the eighth player in history to steal 200 bases before age 25, a stop sign.
Rafael Furcal, SS, Dodgers
L.A. hit the second fewest homers in the NL last season, then lost J.D. Drew and his 20 jacks. That makes Furcal even more important in manufacturing runs. He thinks about the extra base every time he makes contact, which puts pressure on the defense. Furcal's game defines the Dodgers: feisty, aggressive and very fast.
Alfonso Soriano, CF, Cubs
Sure, he could steal 40 bags again, but this year Soriano's speed is essential on D. The ex-2B doesn't get good reads or breaks. Plus, center-fielders handle the ball more than corner guys, and Wrigley Field, with its sun and wind, isn't the Friendly Confines for outfielders. Add it all up, and Soriano will need to outrun his mistakes.
Bob Wickman, RHP, Braves
Because they sit in the bullpen and work one inning at a time, it's not often that closers are team leaders. But there are many things about Wickie that his teammates admire. He cares more than most, he knows more than most and he makes sense when he speaks. Plus, he has overachieved with mediocre stuff.
Eric Chavez, 3B, A's
Last season, forearm problems sapped Chavez's strength and power. Many players would have opted out of the lineup to protect their stats, but Chavez knew the team needed his D, leadership and whatever offense he could provide. The A's made the playoffs by taking on the personality of their gritty and determined third baseman.
Ron Washington, manager, Rangers
He's considered the best teammate ever by those who played with him and the best coach ever by those who have played for him. He makes each person feel special and is a master at uniting a club. Look for the type of impact in Texas that Joe Girardi had as a rookie manager in Florida. Just expect Washington to be around longer.
Steve Phillips, former general manager of the New York Mets, is a regular on ESPN's Baseball Tonight.