Yea the ratings do a little but, it's only as a way of countering the ratings in the matchup.
You only need strength to counter another plays strength. It does actually make players play stronger. If a DL players has 95 block shed they will easily get through the 0 lineman but it's not as easy as he should and it doesn't make him better at using skill or moves to shed blocks.
These ratings should actually make a player better at that skill or ability. RTE should make a receiver better at running routes. The routes look the same. The only thing it does is cause the receiver to "win" the route. Not the skill of getting open it just causes the DB to play worse. So you only need coverage rating for that reason, sadly even with 0 RTE a receiver still has no trouble getting open on curles and outs against a cb with 90 man coverage.
The system needs to be scraped. It's really a NES or SEGA system.