Last week we kicked off our “Key” player series with a look at the “Key” player for each National League East team. We will continue the series this week starting with the National League Central.

Chicago Cubs – Ryan Dempster: The Cubs don’t have too many players with value on their current roster, but Dempster is one of those players who does have some value. Dempster has been a pretty consistent pitcher since 2008, posting a 15.0 WAR over that time period, which is higher than Chad Billingsley‘s, Matt Garza‘s, and Ervin Santana‘s.

The Brewers are asking a lot of Gamel in 2012

Pitchers like Dempster are always in demand come the trade deadline and if he pitches well in 2012, a team like Boston makes a whole lot of sense as a trade partner. The Cubs need prospects in order to help with their rebuilding process.

Cincinnati Reds – Sean Marshall: I had Scott Rolen pegged for this at the beginning of last week, but with Ryan Madson‘s injury, that changes things. Marshall’s performance is really going to be a big part of how far the Reds go this season.

A lot of people can set up games in the seventh or eighth inning, but getting the ball in the ninth and getting the job done is an entirely different story. Sabermatricians don’t believe there is a difference, but anyone who watches baseball in October will tell you differently.

If Marshall can’t handle the closer job, the Reds bullpen might turn into a mess until they are able to get some help.

Houston Astros – Jason Castro: Tough to pick a key player on a team that is expected to lose 100+ games in 2012, but I am going to go with Castro here. Castro was the Atros’ first round pick (10th overall) in 2008 and his development is going to be key to the Astros’ rebuilding process.

Castro missed all of the 2011 season because of a knee injury and getting him back is huge for the Astros.

Milwaukee Brewers – Mat Gamel: The Brewers will never be able to replace the production of Prince Fielder in the middle of their lineup. The guy who is going to be asked to replace Fielder at first is Gamel and while like I said will never be able to replace Fielder, he is going to have to be productive for the Brewers in order for them to get back to the postseason.

Gamel is a career .304/.376/.498 hitter in the minor leagues and if can come anywhere close to that in 2012, the Brewers would be quite happy. Gamel has already popped three HR’s this spring and has an .879 OPS. Expect somewhere around a .250 average for Gamel with a pretty OBP and somewhere between 20-25 HR’s.

Pittsburgh Pirates – Pedro Alvarez: Alvarez was taken with the second overall pick in the 2008 June Draft and so far, he has been nothing short of a disappointment in a Pirate uniform. One could argue that the Pirates really rushed Alvarez through the minors and that he should have never been called up in the first place.

He’s struckout 199 times in 582 career Major League AB’s and if the Pirates are every going to turnaround their losing ways, then they need their high draft picks like Alvarez to pan out. If Alvarez continues on his current path, he will just represent another lost high draft pick for the Pirates.

St. Louis Cardinals – Carlos Beltran: Like the Brewers with Fielder, the Cardinals will never be able to replace Albert Pujols. They’ll try, but it is going to be difficult. Replacing the best player in the sport in never easy.

The Cardinals brought in Beltran in hopes that he has another 2011 season in him. The Cardinals have done well with these older players, who have a history of injuries (See Lance Berkman) and if they get the 2011 version of Beltran (.300/.385/.525 with 22 HR’s and 142 games played) they will be in business.

However, in the previous two years, Beltran played in a grand total of 145 games because of injuries. If that is the Beltran the Cardinals are going to get, then they are going to have a hard time scoring runs in 2012.

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By The Baseball Index