Skater offense peaks early. It only takes about a couple of years for skaters to reach their peak offensive value and once they reach that peak, they start a relatively slow decline until their late 20s where that decline hastens. Defensive value seems to be at its peak basically right when skaters enter the league but declines much slower than offensive value. Value derived from drawing and avoiding taking penalties declines sharply the moment players enter the league. I believe this can be attributed to the idea that drawing penalties is mainly a product of a player's speed and physicality overwhelming opposing defenders, both attributes that are basically in decline the moment a player steps on the ice at the NHL level. When putting these components together and weighting them appropriately, one can yield a total GAR rate. Here is the GAR rate aging curve for all skaters:
Unsurprisingly players peak early in their careers and decline slowly into their late 20s followed by a more rapid decline. Here are GAR rate curves split by forwards and defensemen:
Defenseman retain their value a bit longer than their forward counterparts. Given that offensive and penalty drawing value peak earlier than defense, it is not too surprising that defenseman maintain their value longer when coming into the league because the former two skills are more important to being a productive forward.
Finally, I created a goaltender GAR rate curve. This comes with the disclaimer that "goalies are voodoo" and both NHL teams and public analysts alike have always had trouble gauging the value of a given goaltender. With that being said, using Evolving Hockey's attempt at quantifying the value of a goaltender, here is how goalie value ages:
Goaltenders basically begin to decline the moment they step into an NHL crease. Even with the uncertainty of valuing goaltenders, maybe teams should not be signing 30 year-old goaltenders to massive free agent contracts and long-term extensions. Just a thought and something to keep in mind with Braden Holtby and Jacob Markstrom hitting the free agent market at the conclusion of the Stanley Cup Playoffs.