Roberto Alomar is a lock. Among all second basemen, Alomar ranks sixth in hits, seventh in runs and 10th in RBIs. With 474 steals, he's fourth all-time among second basemen. . Oh yeah, and he could play a little defense.

He won 10 Gold Gloves, tops among second basemen.
Edgar Martinez will not make it. While he did have a .312 lifetime BA, he didn't play a position and he did not achieve any of the "magic" numbers (most notably 3,000 hits or 500 HR's)
Barry Larkin will not make it. Solid player but he was hurt way to much and his numbers reflect this fact. He managed to play in 150 or more games in only four seasons. Larkin spent significant time on the DL in 10 different seasons. If the guy stayed healthy he would have been consider one of the greatest SS of all time.
Fred McGriff will get in eventually. There are exactly a dozen first basemen in the Hall of Fame. Only five of them drove in more runs than Fred McGriff, only four hit more home runs, and only three scored more runs. Mostly, we're talking about Lou Gehrig, Jimmie Foxx, Willie McCovey and Eddie Murray. However, when looking at his era, McGriff's numbers fall short of Rafael Palmeiro, Jeff Bagwell, Jim Thome and Mark McGwire. Considering this was the steroid era, I think McGriff deserves to get in at some point...but not this year.