Last week we looked at some areas of need for NL contenders.  Using weighted on-base average, let's identify the weakest offensive production by position in the AL today.  Since they're all within 6.5 games of the division lead, we're going to loosely call all AL Central clubs contenders.

• Catcher: White Sox (.275), Orioles (.277), Tigers (.278).  The Orioles might prefer Matt Wieters get on base at better than a .297 clip, but most likely they're content with his production.  The team's catcher production has been dragged down by backups Chris Snyder and Taylor Teagarden, who have soaked up about 14% of the ABs and have offered nothing.  The Tigers have used Alex Avila and Brayan Pena, the latter of whom has actually been decent.  It's looking like more of a timeshare at present.  It doesn't seem like acquiring someone like John Buck or Nick Hundley would help the situation.  Tyler Flowers hasn't done much as A.J. Pierzynski's replacement in Chicago, but giving Josh Phegley a look makes more sense than an acquisition.
• First base: White Sox (.284), Royals (.290), Twins (.305).  The Royals have been suffering through another subpar season from Eric Hosmer.  The White Sox are hoping for Paul Konerko to pull out of it, while the Twins have to hope Justin Morneau rediscovers his power stroke.  Corey Hart and Carlos Pena could be available this summer, as first basemen go.  
• Second base: White Sox (.235), Orioles (.237), Royals (.246).  Jeff Keppinger has done much, but the White Sox reinstated Gordon Beckham from the DL today.  The Orioles have used Ryan Flaherty, Alexi Casilla, Yamaico Navarro, and a few games of Brian Roberts before he suffered a hamstring injury.  They might as well wait to see if Roberts really does return in mid-June, and then see if he can still hit.  The Royals have mainly gone with Chris Getz and Elliot Johnson.  Perhaps when Chase Utley returns from his oblique strain in mid-June, the Phillies' chances in 2013 will have tipped the scale one way or the other.  The second base trade market offers little otherwise; perhaps Rickie Weeks or Darwin Barney.
• Shortstop: Yankees (.256), Royals (.263).  Derek Jeter is recovering from an ankle injury, and it's unknown when he'll make his season debut.  The Royals seem locked in with Alcides Escobar.  The trade market appears barren anyway, unless perhaps the White Sox make Alexei Ramirez available.
• Third base: White Sox (.265), Royals (.268), Angels (.282), Yankees (.284).  Have you noticed the Royals get no offensive production out of their infield?  Mike Moustakas is the culprit here.  Conor Gillaspie has been OK at third for the White Sox, and should eat into Keppinger's playing time.  Alberto Callaspo and Luis Jimenez haven't given the Angels much production.  The Yankees have Kevin Youkilis back, plus the possibility of Alex Rodriguez down the road.  Aramis Ramirez, Chase Headley, Mark DeRosa, and Juan Uribe could be available.   
• Right field: Athletics (.252), Royals (.262), Yankees (.280), Angels (.282).  The A's hope Josh Reddick, back from the DL on Friday, will start hitting.  The Royals can't expect that from Jeff Francoeur.  The Yankees have tried Ichiro Suzuki and Brennan Boesch, and now Lyle Overbay is getting a start in right field as the team waits for Curtis Granderson to return to their outfield.  For the Angels, Josh Hamilton at least showed some power in May.  Thinking about the trade market?  Giancarlo Stanton, Andre Ethier, Nate Schierholtz, Alex Rios, and Mike Morse are the commonly speculated-upon names.
• Center field: Twins (.257), White Sox (.292), Tigers (.303).  Rookie Aaron Hicks had six home runs for the Twins in May, so maybe things will continue getting better.  The White Sox have been using Alejandro De Aza and Dewayne Wise, and perhaps should just use less of Wise.  The Tigers await the return of Austin Jackson.     
• Left field: White Sox (.293).  Dayan Viciedo hit 25 home runs last year, but has just four so far this year.  The team has also been using De Aza in left.  Josh Willingham, Jason Bay, Raul Ibanez, Carlos Quentin, Alfonso Soriano, and Melky Cabrera could be on the market, in a general sense.
• Designated hitter: Tigers (.263), White Sox (.284), Orioles (.308).  Big commitments to Victor Martinez in Detroit and Adam Dunn and Konerko in Chicago hamstring this clubs at DH.  The Orioles may want to see what Nolan Reimold can do when he returns later this month, but they should be flexible toward upgrades involving many of the aforementioned available hitters.  As far as pure designated hitters, Kendrys Morales and Adam Lind might be out there. 

Even contenders have their flaws.  Defining contenders as any team Clay Davenport gives at least a five percent chance of reaching the playoffs and using weighted on-base average, let's identify the weakest offensive production by position in the NL.

• Catcher: Reds (.263), Diamondbacks (.265).  For the Reds, giving Devin Mesoraco the clear starting catcher role over Ryan Hanigan would boost their offensive production out of the position, but of course this position is about a lot more than hitting.  The D'Backs are in a tough spot.  They have a major commitment to Miguel Montero, and he's been brutal so far this season.  They probably just have to hope he pulls out of it.
• First base: Rockies (.289), Phillies (.317).  The Rockies have used Jordan Pacheco, Todd Helton, and a little bit of Michael Cuddyer at first base this year.  In theory, the Rockies could go with Cuddyer at first and someone like Tyler Colvin in right field.  The trade market is bleak at the position, as Justin Morneau and Carlos Pena would not be clear upgrades for Colorado.  Corey Hart could be an interesting option, once he comes off the DL.  The Phillies owe Ryan Howard roughly $98MM through 2016, so they'll just have to hope he can start drawing some more walks and begin to add positive value.
• Second base: Nationals (.227), Diamondbacks (.284).  Second base has been a black hole for the Nats, with Danny Espinosa and Steve Lombardozzi struggling.  Fans are calling for the return of 2011 first-round pick Anthony Rendon, but he probably needs to gain more experience at second base first.  The D'Backs have used Martin Prado at second baes a decent amount in Aaron Hill's absence.  Should Hill require surgery on his hand fracture, perhaps the D'Backs will look into an acquisition.  Maybe third base prospect Matt Davidson, hitting .311/.342/.544 at Triple-A this month, could help the situation.
• Shortstop: Dodgers (.219), Pirates (.248).  Hanley Ramirez should return from a hamstring injury next week, providing a lift to the Dodgers' abysmal offensive production at shortstop.  The Pirates signed Clint Barmes in the 2011-12 offseason for his defense, but it barely makes up for the automatic outs at the plate.  Jordy Mercer, John McDonald, and Chase D'Arnaud aren't much better, and highly regarded prospect Alen Hanson is still at High A.  Good luck finding a decent-hitting shortstop on the trade market, though.  The White Sox, should they drop out of contention, could offer up Alexei Ramirez at a premium.
• Third base: Pirates (.259), Rockies (.280), Dodgers (.288).  It's been a power-only show for the Pirates' Pedro Alvarez at the hot corner, as he's striking out a ton and owns the fifth-worst qualified OBP in the NL (.257).  Aramis Ramirez would be a fun pick-up, though intra-divisional trades can be tricky.  Chase Headley would be a huge addition, but only if the Padres are willing to listen.  The Rockies will give rookie Nolan Arenado some time to find his footing.  Less Luis Cruz should be enough to give the Dodgers a lift.
• Left field: Diamondbacks (.300), Reds (.300), Giants (.302).  The D'Backs have used six different left fielders, and figure to stick with Jason Kubel and Cody Ross.  With Ryan Ludwick and Chris Heisey on the DL, the Reds have been employing Xavier Paul of late, and he's been solid overall.  The Giants' combo of Gregor Blanco and Andres Torres was never meant to be offense-first, and Torres has heated up in May anyway.  Should one of these teams turn to the trade market, Josh Willingham, Carlos Quentin, Michael Morse, Jason Bay, Raul Ibanez, Melky Cabrera, and Alfonso Soriano are some candidates.  Several of those players don't work for the Giants, however.
• Center field: Dodgers (.278), Braves (.278), Phillies (.288).  Center field is not an offense-first position, but in general these teams just need to get more out of their incumbents.  Matt Kemp might miss some time with a hamstring strain, which could allow for Joc Pederson to get a look with the Dodgers.  It seems crazy for the Braves to push B.J. Upton into a full-blown platoon with Jordan Schafer months after committing $75.25MM over five years, but that could be an option at some point.  The Phillies were looking mostly for defense from Ben Revere, but .263/.302/.294 is still tough to stomach.  John Mayberry Jr. can pitch in a bit.  As for the trade market, Peter Bourjos, and Franklin Gutierrez could become available when healthy.  David DeJesus, Chris Coghlan, and Alejandro De Aza could also be options.
• Right field: Phillies (.294), Braves (.313).  Delmon Young hasn't done much for the Phillies in right so far.  The Braves' Jason Heyward has been terrible, and we'll see how long they can wait that slump out.  Trade options could include Giancarlo Stanton, Alex Rios, Andre Ethier, Nate Schierholtz, Chris Denorfia, Morse, and Hart.