Grinding for no reason

Ok so this is where me and madden goes wrong at..how I can sit and grind for days and months and some body with a 80 overall can have the best coverage on defense.. I have  three 99 wr.. 99 speed and acceleration 99 deep route... My wr’s are on lock with a 80 overall defense.. So I grind day in and day out just for some 80 overall defense to just come and lock my wr’s down .. please Enlighten me ea sports.... do tell!!!..p.s  all their db’s speed is mid 80s and zone and man is high 80s ... starting to hate this game