i don't have a lot of experience with players over the age of 32, and the two players the Chargers just placed on the TL showed me something of the unpredictability of their declines. Blake has been earning $58,000, which is a ton of money for a SF, but only has what we could call a modest skill set (a pretty good player at the right price) -- but i have an addon that estimates his salary now at $44,000 -- the declines in some skills (i'm guessing JS / JR) must have been impressive.
on the other hand, another 34 year old, Xiang, still looks to have all his skills -- 126 skill points, still a very impressive player. (my salary estimator addon suggests he lost no skills this season.) but next season? my experience is so limited that i don't know how fast players drop: 5 skill points a season? 10? it does seem to me that beginning at 126 sp would guarantee a decent player for at least another 3 seasons or so, but i don't know how much i would spend to see if that were true.
it will be interesting to see what the market thinks of those players.