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Sahadev Sharma is a contributor to ESPN Chicago and ChicagoSide, where he regularly covers the Cubs and White Sox. Sahadev spent four years as a radio producer at ESPN 1000 in Chicago and often dabbled in the blogosphere. In the fall of 2010, Sahadev focused his attention on the writing side of the business and quickly realized that was where he belonged. If not spending his free time with his wife, one-year-old son, and two Italian Greyhounds, you’ll likely find Sahadev appreciating Starlin Castro’s ability to hit, defending Adam Dunn, or watching YouTube clips of the Illini’s 2005 NCAA tourney comeback against Arizona. Follow him on Twitter @sahadevsharma.

A week ago, Chicago Cubs fans got their season-long wish of seeing Anthony Rizzo step into the batter’s box and take his first swings at Wrigley Field as a part of the big-league club. Rizzo delivered with a single in his first at-bat and followed that up later in the game with a double that knocked in the eventual game-winning run. It was love at first swing.

A little over two years ago, Cubs shortstop Starlin Castro made his major-league debut with a loud crack of the bat as well. Castro homered in his first plate appearance and added a triple in a debut that seemingly announced the arrival of a future star. But with Cubs fans currently agog at the arrival of Rizzo, Castro has become the forgotten child.

Seven months Rizzo’s junior, Castro is already heading to the second All-Star game of his young career. But in a rather strange turn of events, during a season in which the North Siders are on pace for a feeble 60 wins, Castro has become a sort of whipping boy for some. 

When previewing the Cubs’ 2010 top prospects, Kevin Goldstein wrote that Castro “has an instinctive knack for contact and rockets balls from line to line with regularity.” Castro has shown that ability to hit, posting a .300 or better average in each of his first two seasons and hovering around that mark for the majority of this season.

But that batting average has been a little empty, as his career high in slugging percentage, which he achieved last season, is just .432. Couple that with his steadily declining walk rate (5.7% in 2010, 4.9 in 2011, and currently 3.3 in 2012), his at-times shaky defense, and the occasional mental mistake, and one gets a snapshot of why Castro, while still considered the best player on his team, is also one of the most criticized.

If the Cubs’ President of Baseball Operations, Theo Epstein, is going accomplish his goal in Chicago— turning this moribund franchise from a yearly punching bag into a perennial contender—it’s Castro, not Rizzo, who will need to be the centerpiece of the team.

What people often overlook, mainly because he’s been performing at a high level for over two years now, is that Castro is only 22 and just scratching the surface of his true ability.

“Castro needs to improve in the plate discipline department, but I think that's going to come when he learns to drive the ball with more consistency,” said one area scout. “Power often breeds plate discipline as pitchers pitch guys more carefully that consistently hit the ball with authority. I think he needs to get a little better at looking for a pitch he can drive, especially early or ahead in the count, rather than putting in play the first strike he sees.”

The area scout pointed out that he’d like to see that change in plate approach happen soon. Otherwise, there will be some concern that it may not happen. Castro had only six walks in his first 312 plate appearances on the season. In his last 24, however, he’s had five walks (one intentional), and his approach has looked considerably more patient. Part of that could just be dumb luck associated with a small sample size, but hopefully for the Cubs—who recently fired hitting coach Rudy Jaramillo and brought in James Rowson, who is preaching a slightly more selective approach—it’s a sign that Castro has begun to mature as a hitter.

“He has the tools to become a more patient hitter, he has the tools to be develop some more power,” said a pro scout who was befuddled by the criticism directed Castro’s way. “I’m willing to believe in a player at that age and with his tool set. I still believe in the kid. The ability to play that position and the ability to hit, there’s just not many guys out there that have his skill set that play the middle of the infield. That’s something that’s lacking in the industry, and when you find it, it’s valued.”

While Castro is currently playing in the middle of the infield, there are questions as to whether he can stick at shortstop in the long term. Though most advanced defensive metrics suggest that Castro is playing the strongest defense of his career, it’s still assumed that eventually he’ll be moved off the position.

“I think even the most optimistic Castro supporters didn't think he had the super fast twitch body that would hold up long term at shortstop, so I think his time is limited there,” said the area scout I talked to. “Where's his future home? Well, since the OPS of second basemen and third basemen is mostly negligible now, I don't think it matters much. But I think he's got the hands, first step, and arm that he'll be a fit whichever direction he has to move.”

In 2011, second basemen actually out-OPSed third basemen .708 to .705. But that’s changed drastically in 2012 (.733 to .697 in favor of third basemen) mainly due to a healthy David Wright, position changes for Miguel Cabrera and Hanley Ramirez, and the emergence of the likes of David Freese and Mike Moustakas. Regardless, if Castro’s bat continues to develop, it would likely be of value at either position.

As the pro scout I spoke with said, players will let you know, not with their words, but with their play, when they’re ready to move off a position. Castro is not at that point yet, and it’s not like the Cubs have a hot-shot young shortstop ready to take over in the next few years.

“The industry’s not littered with guys with whom you’d say you have to move Castro off shortstop,” said the pro scout. “There are some guys, but there aren’t a lot.”

Castro is far from perfect, but with Rizzo garnering all the attention of late, it’s as if people have forgotten just how valuable Castro truly is to the franchise. The first symbol of the Cubs’ (hopeful) future triumph may have been Rizzo’s call-up to the big leagues. However, the most important step could come  this offseason, when Epstein and General Manager Jed Hoyer should attempt to lock up Castro to a long-term extension.

“Rizzo, the jury is still more than all out on him,” said the pro scout. “Castro’s proven his worth a bit. When you build a team, you’re going to build around starting pitching and premium position players. That’s why I’d lean towards Castro at this point.”

Signing Castro this offseason would have numerous benefits. First of all, the Cubs would be securing the services of one of the more talented young bats in baseball, hopefully eating up his arbitration seasons and, if they’re lucky, a free agent year or two as well. Most importantly, they would be doing it before he’s reached his peak value, thus likely getting him at well below his true market value for years to come.

Of course, that doesn’t mean this type of maneuver comes without any risk.

“You look at the Indians signing (Grady) Sizemore and (Travis) Hafner, they looked great at the time, but they didn’t pan out,” said the pro scout. “You look at what the Padres have done with (Cameron) Maybin and (Cory) Luebke, team friendly deals, younger guys who they project on. I think Castro kind of falls into that mold a little bit. If they can sign him to a deal that locks him up and protects him in the future, that’s definitely something the organization should look into.”

Having the ability to spend money on free agents is important, but being able to keep your own players at below market value is essential, especially if Epstein wants to achieve his stated goal of building a foundation of sustained success. If the Cubs can accomplish that, it will give them more money to go out on the market and spend on elite free agent talent when they’re actually ready to compete for a playoff spot. Extending Castro could be the key to making sure that Epstein and Hoyer bring the success they shared in Boston to Wrigleyville.