So, I have the opinion that both Defensive Line and Offensive Line have a law of increasing returns. What I mean is that the more talent you have there, the more return you you get on each increase in talent. If you have an average defensive line with one stud like Myles Garrett, there are ways for offensive coaches to scheme around that. However, for each defensive lineman you add who can regularly beat his man one-on-one, the ability for an offense to gameplan against your strengths diminishes, and the impact each defensive lineman (or the unit as a whole) has on the game increases. I feel we saw this in action with San Francisco this year, where their defensive line controlled the game.
I think this goes for the offensive line as well. You stick a Joe Thomas at LT, but put crap in other positions, and you're gonna get crap out. For each guy you put in that can consistently win his matchup, you allow every other person to excel even more at their individual jobs. If you don't have to cover for the guy next to you, you can be better at your own task. I feel we saw this with Dallas before injuries started to take their toll on that offensive line.
So, while I think there's talent to be had at safety and WR, I'm completely on board with improving our RG or DT positions.