Funny you should ask about defensive linemen; I've been pondering this aspect for some time and was considering posting about it anyway.
From
what I've seen,
defensive tackles are not playmakers in this game, so in my opinion spending lots of money on awe-inspiring DTs like Quincy Sims or Devin Gilbert is not a wise use of cap space. STR 85+, SPD 60-70, ACL/AGL 60-80 is plenty good for physical attributes; an ATH grade over 80 is a good general benchmark.
Ends are much more difficult to evaluate. The ATH grades for ends are all over the map: an 80 grade can be a terrible end or a pretty decent one, depending on the underlying stats. In my schemes, ends need to compete with offensive tackles, so they need similar/better stats: STR 85+, SPD 70+, ACL/AGL 70+ are my general ballparks. A 70 SPD end is low, but manageable; 75 is average; 80 or better is good speed. Likewise 80 is a low-STR end, and 90 or better is really good. A low-speed low-strength end will be worse off than many linebackers in the game and won't be worth playing, so any end you draft should be good at
something or at least average at everything.
For example, in my current career my Packers have a RE from Florida State with STR 95, SPD 71, ACL 77, AGL 68 and an ATH grade of 79; a LE from Connecticut on the squad rates an ATH 80 with STR 86, SPD 75, ACL 89, and AGL 86. These guys are both players; the former is more of a run-stopper, but they get the job done. There are worse ends with higher ATH scores, and potentially equal-or-better ends with worse ATH scores (say, Victor Abiamiri). In the English path, the LE UNLV sleepers all rate an ATH 83. So around ATH 80 for DEs is worth close examination; not until ATH 85 can you be pretty confident that a player has the physical skills to flourish in most systems.
For all defensive players - actually, for starters period - learning in the mid- to upper-80s should be high enough, particularly as you grow your defensive playbook and get special learning enhancement skills for your coaches. And naturally, you want all your DLs to be able to shed blocks, rush the passer, stay healthy, etc. for their intangible grade: generally 80 or higher would be desirable.
I'll address my defensive "big picture" in another post.