I'm convinced it is impossible for an offensive lineman to upgrade his dev trait
I've played a ton of seasons of Dynasty, and I've seen dev trait upgrades from every position group at least once, with the exception of K/P and OL. To test this out further, I started a Dynasty with Georgia as Kirby Smart, since he's a very high level coach with CEO, which let me unlock Gainz Getter. I simmed through 30 seasons, and got dev trait upgrades from every position except LB (not counting K/P, this is the second-rarest position group for this in my experience), OL, and K/P. Usually averaged 1 upgrade a year total and never had more than 2 in one offseason.
I even tried things like getting Talent Developer for OL so they'd grow more, thus play better, and be more likely to outperform their dev trait. I tried benching Star and Elite OL for Normal and Impact. I tried the coaching perks that make you more likely to persuade and/or retain players. My logic there was that guys who had great seasons could now be forced to stick around and potential go up in dev trait. None of it worked for offensive linemen.
I think that a lot of the dev trait upgrades are linked to stats, and OL don't really have individual stats the game can use for this.
Have any of you noticed this as well?