Offensive lines can get better. There are a ton of NFL lineman that grade out the same on the track events. As we saw with Greg Robinson, that just being slightly stronger doesn't make you better.
You need to think on your feet and have good technique.
I believe Offensive line can be developed more so than the skilled positions that are based on speed and ability. Being a good offensive lineman is about being reliable and showing up for work from 8-5 and doing the same thing over and over the right way. You need to do the right thing 20 out of 20 times vs 18 out of 20 times where there are 2 disasters that blow up the game. You don't have to win the physical battle all 20 plays, but you have to do the right thing. Know the plays, know the opponent, and have a good foundation with good technique.