Mets' prospect Fernando Martinez is now batting .538 in spring training, with 3 home runs. His 14 hits and 29 total bases are among the most in exhibition baseball this March, and he is one of a number of young Mets who have excelled in spring training and given the team, and its fans, some genuine cause for encouragement. ?Last year, I tried to do too much,? Martinez said, referring to his 29 games with the Mets in 2009, when he hit .176 with a home run before going on the disabled list. Yet because Martinez is still just 21 years old, and needs to play every day, Manager Jerry Manuel seems reluctant to keep him on the team come April. He is more likely to start the season at Class AAA Buffalo, where he is guaranteed a lot of at-bats and plenty of chances to improve his skills as an outfielder, particularly in center. ?The center-field part is very important right now,? Manuel said, referring to the need for the Mets to have a good anchor in Citi Field?s cavernous outfield.