I've kept a Career Extension guy for the past few seasons, and that definitely helps but I've still had quite a few... probably averaging a little more than 1/week.
Some guys have been hit a lot harder than others for some reason. Jair Rodriguez has had more drops than other 35 year olds or even my 36 year old. Also, Arthur Glass dropped in just enough skills to prevent a late career NT call up last season :(
I haven't noticed a higher % so far this season though.