Aside from the J.J. Putz trade, the Seattle Mariners organization has had a fairly quiet off-season despite its disappointing 2008 season and 61-101 finish. Haunted and hindered by some poor contracts (Miguel Batista, Carlos Silva, Kenji Johjima), the club has made only minor adjustments to the 40-man roster via free agency with the acquisitions of corner infielder Russell Branyan, and reliever Tyler Walker. The club also selected Rule 5 draft pick Reegie Corona, a middle infielder.
Hernandez was originally selected out of a Miami high school in the third round of the 2004 amateur draft by the New York Mets. He was then traded to the Florida Marlins for veteran catcher Paul LoDuca in December of 2005. In July of 2008, the Marlins shipped Hernandez to Seattle for ancient reliever Arthur Rhodes. The 22-year-old has excellent stuff – including an 88-93 mph fastball, plus curveball and change-up – but his results have been inconsistent. Hernandez began 2008 in Triple-A but was lit up. He allowed 94 hits in 64.2 innings and posted reasonable rates of 3.62 BB/9 and 7.52 K/9. He also allowed 14 home runs (1.95 HR/9). Hernandez was demoted to Double-A where he went 3-0 in four starts with an ERA of 4.30. The trade to Seattle followed and Hernandez was again assigned to Double-A, where he posted a 5.01 ERA in six starts. Overall on the season, he allowed 154 hits in 121.2 innings, with rates of 3.33 BB/9 and 6.95 K/9. Right-handed batters hit .327 against him. He was equally ineffective in the Arizona Fall League with 33 hits allowed in 29.1 innings and an ERA of 7.67.
Kahn was an interesting addition to the 40-man roster after missing all of the last two seasons with ACL tears in both knees. Despite having thrown just 14.1 innings since 2006, he took a valuable roster spot. Those 14.1 innings came in the 2008 Arizona Fall League, where Kahn allowed 18 hits, 10 walks and struck out just nine. There was no need to add the right-handed to the roster considering his terrible command and control – which have always been bad and will definitely not be helped by the time off. Even with a fastball that can touch 95 mph and a good curveball, it’s unlikely that a team would have taken a Rule 5 risk on him, nor would he have survived on a Major League roster for the entire season.
On the plus side, Vega has pitched in both of the last two seasons but, like Kahn, he was added to the roster despite his inability to find the strike zone. His rates from Double-A in 2008 include a 5.77 BB/9 and a 6.55 K/9. That creates a stunning 1.14 K/BB rate. The right-handed reliever allowed 67 hits in 68.2 innings and gave up just three home runs (0.39 HR/9). The Colombian throws 91-93 mph with an average breaking ball and change-up.
Wilson parlayed a breakout 2008 season into a 40-man roster spot. The 25-year-old outfielder posted a line of .276/.388/.549 with an ISO of .273 in Double-A. Some caution must be taken with his numbers, though. He was old for the league and it was his third attempt at the level. At 28.8%, Wilson did a nice job of reducing his strikeout rates from 2007 (42.8%) and 2006 (34.1%). The outfielder has definite flaws and will likely never hit for average at the Major League level, but he would have become a minor league free agent if he had not been added to the roster. This buys the organization a little more time to ensure 2008 was indeed a fluke.
Halman, on the other hand, is an outfielder who is oozing with undeniable potential. The 21-year-old split the season between High-A ball and Double-A and hit 29 home runs and stole 31 bases, making him a 30-30 threat. Like Wilson, though, Halman does not currently project to hit for average after batting .268 in High-A and .277 in Double-A (as well as a career .262 average). To succeed at higher levels, he will also need to take more walks after posting rates of 5.9 BB% and 6.4 BB% this past season. He looks like Mike Cameron without the Gold Glove defence or Chris Young with less patience.
Marc Hulet has been writing at FanGraphs since 2008. His work focuses on prospects and fantasy. Follow him on Twitter @marchulet.