I harp on certain position coaches all the time BUT "developing talent" can mean a lot of things, IMO. Most college players are considered "raw" or underdeveloped or "they need time to develop, etc.
The best "teams" at developing talent might be great in one area and not so much in another, hence the word TEAM.
IMO, position coaches "develop" talent which includes making a player better AND recommending their strengths to the OC/DC for play-calling and positioning. Some are good and some are really not good. We have an OL coach that has seemingly done the impossible of making good players worse (they were better on other teams, either college or NFL)
Our WR coach last year sucked as well, almost everywhere he's coached. He MAY have been able to teach the scheme but he couldn't teach discipline...and he is gone now.
We have a weak DC, whose coaching history is dubious at best. Maybe that's all we can get BUT we saw what positive influences Brian Flores had on play schemes.
We have a much better OC now, though we couldn't have gotten worse. Time will tell if he is better suited as an OC, "obviously".
Our DL coach hasn't done much with anyone other than the "already good" players. His history at BAMA was not necessarily a great resume, as he was always loaded with talent.
Our secondary and LB coaches starting last year was pretty good considering all they had to deal with injury-wise.
Sometimes "development" means playing to the strengths that the position coaches claim. A great example is how some of our players (Sutton, Dupree, Willie Gay, Bryant McFadden, LeVeon Bell and JuJu) all left and got worse, some returned and got better. THAT is knowing your players strengths and playing into them. While others like (Kevin Dotson, Manny Sanders, James Connor, Kraig Urbik, and others) played better with their new teams which shows a lack of development or play position/scheme.
Bottom line, the ONLY good thing about our HC is that for whatever reason, players want to play for him and most respect him. He is just too confident in his own coaching ability and meddles too much. He also is usually too loyal to players and coaches that make him look bad as a leader.
Teams that have been better at developing talent are usually the ones with the best position coaches and coordinators. (Philly-OL, 49ers/Texans-offensive skill players, Ravens - DL, Bills - DBs). We have a better OC and hopefully WR coach, so we shall see.