Why don´t you like the plan of career ending injuries with an increasing probability starting at a certain age? Maybe the proposed 29 is too young, but if it starts somewhere around 31, you are (1) warned and (2) to some degree prepared.
Sure the randomness sucks, but if you invent a "halbwertszeit" of maybe 3 seasons (which means starting at age 31, till the player reaches the age of 34 50% of his generation will be out due to career ending injuries, then 37 another 50 % out (for a total of 75%), then another 50 % till 40 ...) it kinda reflects the natural aging and "leaving".
Zwei Dinge sind unendlich, die Dummheit und das All...