Jeremy Bonderman

While the relative strength of the National League compared to the American League is debatable, it's hard to deny that the Senior Circuit is more appealing to pitchers. Replacing the pitcher in the lineup with a designated hitter makes AL lineups more potent, as this year's offensive statistics showed – five of baseball's top six run-scoring teams in 2010 play in the Junior Circuit.

The difference may be negligible for certain players, but each year there are usually a few pitchers who switch leagues and immediately see their numbers rise or fall accordingly. After being dealt from the Indians to the Cardinals this season, for instance, Jake Westbrook posted a 3.48 ERA and 6.6 K/9, compared to his Cleveland marks of 4.65 and 5.1.

So although there's no guarantee that starting pitchers will enjoy more success playing in the National League, here are five potential free agents who may benefit from signing with an NL club:

• Javier Vazquez: Of all the pitchers who switched to the American League last offseason, Vazquez suffered perhaps the most drastic setback. After finishing fourth in NL Cy Young voting in 2009, the 34-year-old pitched so poorly this season that he lost his spot in the Yankees' starting rotation. Even taking into account his first two up-and-down years with the Expos, Vazquez's career NL numbers (4.02 ERA, 8.1 K/9, 2.3 BB/9) are better across the board than his AL totals (4.65, 7.9, 2.7). Vazquez won't be back in the Bronx, and his best shot at decreasing his 2010 longball rate (1.8 HR/9) and returning to form might come in the NL.
• Kevin Millwood: We heard earlier this year that Millwood could seek a pitcher-friendly environment for 2011, after years of pitching in Baltimore and Texas. The move makes sense for the right-hander; he still has some value as a veteran innings eater, but could potentially be much more than that in a park like Petco in San Diego. We don't know what kind of contract the 35-year-old will be seeking, so it's possible he could be too expensive for a team like the Padres. For what it's worth though, San Diego was thought to have interest in Milwood in August.
• Jeremy Bonderman: One of the youngest arms on the open market, Bonderman could be an interesting fourth or fifth starter for a team willing to take a flier on him. Though his 4.89 career ERA is uninspiring, he's a former first-round pick and will turn 28 next week. His career peripherals suggest that he still has potential, and he strikes me as the type of pitcher who would benefit from the tutelage of a pitching coach like the Cardinals' Dave Duncan. The Cards may re-sign Jake Westbrook or look elsewhere for starting pitching, but St. Louis isn't the only possible landing spot for the long-time Tiger, who could benefit from a change of scenery.
• Bruce Chen: The 33-year-old journeyman has experienced an unusual major league career, playing for six National League teams before arriving in Boston in 2003. Since then, he has played for four different American League clubs. Chen's career numbers are relatively similar in both leagues, but coming off a successful season in Kansas City, perhaps a return to the NL could be in the cards. While the left-hander has lost some velocity on his fastball since he last played in the Senior Circuit, he's gotten by relying more on flyball outs and less on strikeouts. For a team in a pitcher's park, Chen could be a worthwhile back-of-the-rotation addition.
• Rich Harden: Although a healthy season would help Harden's stock more than changing leagues would, moving to the National League certainly wouldn't hurt. While the right-hander excelled in Oakland when he was healthy, his second stint in the AL wasn't as impressive; his 5.58 ERA for the Rangers this year was by far a career-worst. Still, like Bonderman, Harden is relatively young, turning just 29 next month. He also had stretches of dominance in his time with the Cubs in 2008 and 2009, striking out 11 batters per nine innings and posting a 3.31 ERA in 212 innings over the two years. Again, health is the big concern with Harden, but an NL team may feel more comfortable taking the risk than an AL one would.