I used to raise the catching skill of DB's by 5 using JD's editor but I learned that 5 years down the road you might have issues with too many interception because the DB's catching skill are too well developed. Thats why now before I start playing I sim through the first 5 seasons of a league so that the players are well developed and I am not having issues with dramatic changes in gameplay down the road.
That is a good point.
In an advanced league with different age players, the veterans have some better skills.
It may be worth running the defenders' catching skills through a bell curve though.