So the rumors/current beliefs seem to be that Carlos is wanting at least a 10 year deal, which puts would put him under contract from age 27 to age 36.
This year, the oldest SS in the league is 34--Brandon Crawford and a few others. Crawford is having a great year, and is in the last year of his contract.
Cal Ripken had a pretty good WAR until he was 35 (peaked at age 30), and then he dropped off pretty hard after.
A-Rod is similar--peaked at 29 and 31, slow respectable decline until 35, dropped off 35+
Ozzie Smith is a bit of an outlier, playing SS at an AS level until 37, and even respectable until 39.
Jeter played high level until 35, and then dropped significantly.
Nomar dropped off pretty hard after 30.
Before digging into the numbers, I thought it would have been idiotic to give a SS a contract until he was 36. I don't think the Astros will do it (they haven't done and/many long contracts), but after looking
at some other players, the production levels from shortstops seems to drop significantly around 35. 1 year of a boat-anchor contract doesn't seem too bad. Of course, that's assuming he can stay healthy (big if) and he continues on the same path he's been on.