First off, I agree with you as my teams are almost always rated over 94 after a couple seasons and then next closest team will be like an 85. They never put in their rookies unless they can start immediately or due to injury. DB progression is a joke because they only improve on awareness and nothing else. So once a DB maxes out his awareness, that is as good as he gets (kinda rediculous when you have a first round rookie maxed out at 79 by the end of his first year). The CPU does do a terrible job drafting, with the exception of one team that will face me in the Super Bowl 5 times out of six before its core retires.
For my own experience I simmed 30 seasons w/ the Bills and I got Tim Euhus up to a 94 overall at TE. Bledsoe got hurt in 04 and Losman quickly jumped to a 99 within 3 years. Henry held on to his job and turned out to be a 99. all five of my lineman (JJ, Ross Tucker, TT, CV, +MW) were at 99. MY receivers were 98,97,91 (EM, LE, Antonio Brown). My Defense was good (I drafted DT's in the first round to get rid of PW, SA) and they were 99 and 94 overall. Kelsay and Schobel were both 92's My Backers were stacked with Spikes and Fletcher being 99's and a shifted angelo Crowell as a 97. My Secondary I had to work on in training camp so much. Clements and milloy were 99's. Wire(FS) was a 94 and McGee was a 93. And you have to suck not to have kickers that aren't 99 overall after a couple seasons. Once the players got really old, I would let them go, and draft replacements or I would trade them for picks, so i continously had top 10 picks every year.
I found a true cheat about 20 years in while in cap trouble, where you can switch the players position so they sign for cheaper. Also, You can find Linebackers that are better as D-Lineman or WR better as DB's or TE's and HB's better as FB's .