Bad Luck, his BABIP was terrible this year. If it normalized, his BA would be near or at his career average of .274. Then take the 21 HRs, 30 SBs, 100 runs, and 77 RBIs, and he's an elite SS. Now he's not an MVP caliber guy anymore, but for a weak SS position, there isn't much else out there.
Hanley, Reyes, and then who? Drew took a major step back. Jeter had a great season, but is 4 years older. Tulowitski is really the only I one I can think off.