In 2011, the Mets scored 718 runs, good for sixth in the National League.  They also surrendered 674 earned runs, good for fifth worst in the league.The Mets scored those runs without Ike Davis, a half season from Carlos Beltran, and only 389 at-bats from David Wright and 391 from Daniel Murphy.  So, it stands to reason that a Mets lineup with a healthy Davis, Murphy, and Wright (and Jose Reyes?) will score some runs in 2012.  What they must improve upon is preventing runs.  That means the pitching staff needs to step up and/or needs an upgrade.The bullpen and starting rotation both need help.  An upgrade of the starting rotation would help both.  More innings will take pressure off of the bullpen.  The Mets have some prospects, such as Zack Wheeler, Matt Harvey, Jeurys Familia, but they are not projected to make the major league team until at least 2013.  Johan Santana may or may not be ready for opening day.  The nature of an anterior capsule injury is unpredictable - just look at Chien-Ming Wang.But there are some potential free-agent bargains that the Mets could turn to for starting rotation depth.Erik BedardBedard split his time with the Mariners and Red Sox in 2011.  He compiled a 3.62 ERA and 1.28 WHIP.  Those numbers would have been second only to R.A. Dickey among Mets starters.  Plus, Bedard has a track record.  He was a double-digit winner for the Orioles in 2006 and 2007, and his lifetime ERA is 3.70.As far as his salary is concerned, he made $1MM last year - a mere bag o' shells, even for the Mets.  Depending how the free agent market goes, that price is not likely to change much.His downside - he had injury problems in 2008 and 2009, then he missed the 2010 season entirely.  He rebounded this year to throw 129 innings in 24 starts for Seattle and Boston.The verdict: If his price tag stays about where it is, sign him.Edwin JacksonJackson changes uniforms more frequently than a presidential candidate changes his mind.  Edwin played for 3 different teams from 2010-2011, and has played for a total of six in his big league career.  Most recently, he found himself on the mound for the world champion Cardinals.He went 12-9 with a 3.79 ERA and 1.44 WHIP for the White Sox and Cards combined.  Like Bedard, he also has a track record, including an unlikely no-hitter in 2010.  In that game he walked 8 and threw 149 pitches.  Maybe the Mets could use some of that positive no-hitter mojo.  He also throws a lot of innings: 214, 209, and 199 over the past three seasons.His downside - he tends to put people on base.  He gave up 225 hits in 199 innings in 2011.His 2011 salary was $8.75MM.  If he demands close to that again, he may be too expensive for New York.The verdict:  His price tag will probably be more than he is worth.  Pass on this one.Either Bedard or Jackson can help the starting rotation in 2012, bridging the gap until the young guns arrive.