Ruben Tejada is among seven Mets players who is attending a four-week fitness camp this month in Michigan. Lucas Duda, Wilmer Flores, 2013 first-round pick Dominic Smith, and three other farmhands are also participating. Mets general manager Sandy Alderson said Tuesday that it was completely voluntary and expects some to go back in January. Tejada's involvement comes at an interesting time, as he's reportedly mulling over filing a grievance against the Mets due to a service time dispute. Meanwhile, the Mets are looking into possible replacements at shortstop.