you absolutely have to factor cost into the draft grade. You have to consider your team needs, and how well you addressed them.
So you can't just look at Bush alone. You must consider that you had to give up your 2nd rounder to get him. That was likely the reason why no pass rusher was drafted until late.
Maybe, but the Steelers also left a pretty good pass rusher on the board in the 3rd round (Winovich). If the Steelers stay at 20, they probably go CB and get Murphy? Or if they in fact value an edge rusher, they take Sweat. But they apparently don't think they need a high-end edge rusher, so no Sweat.
Say they go Murphy. Then they can go pass rusher in round 2 and get ... Zach Allen or Chase Winovich, the two best pass rushers to go between pick 52 and 66, when the Steelers had their next pick. So the entire process in your analysis depends on getting Sweat, who is an edge rusher where the Steelers passed on a pretty good edge rusher at pick 66.
If you ignore the value of picks then why not just trade up every single year? A top 10 player is more talented than a guy picked at 20, so why not give away the 2nd round pick every single year to move into the top 10 and grab a better prospect?
Two points, one of which you basically ignore in your statement. First, the team needs to look at the talent pool, and their needs, short and long-term. ILB was a crying need, in the 2018 draft and the 2019 draft. The Steelers basically ignored the need in 2018. Not a good move. You point out that the team could have moved up in 2018 and drafted an elite ILB in Vander Esch.
Agreed. But they didn't. They sat in place once again, and because they were drafting at 28, saw the elite players drafted ahead of them. So move to 2019 ... do the Steelers once again watch the LB'ers go off the board? Apparently yes. They draft ... who, Sweat? He is not an ILBer, tape. He is incredibly gifted, like Tremaine Edmunds in 2018 - another OLB'er. So who? Murphy? Okay, good selection.
And the middle of the field remains a cancer. Oh, look, another TE running free. Wow, another slow ILB'er chasing a slot receiver like Charlie Brown running towards the football.
Second, in my estimation, the best ILB'er in the 2018 draft was Roquan Smith. He went 8th. To move from 28 to 8, the Steelers would have needed to trade (wait for it) their 1st round pick in 2018, their 2018 2nd round pick, their 2018 3rd round pick, and their 2nd round pick in 2019. Would you have dealt that for Smith?
Smith is 6'1", 236 lbs., ran a 4.51 40, has 32" arms. Bush is 5'11", 234 lbs., with 32" arms, ran a 4.43 40, posted a 40" vertical, 124" broad jump.
The two guys are about as close to one another as I can imagine. The knock on Smith? "Too small to play inside." Yeah, sure. He had 121 tackles last year, 5 sacks, 5 passes defensed.
So to sum up: Moving up in 2018 to get the only true ILB'er would have cost a lot more, to get a strikingly similar player.
Third, should the Steelers have moved from 28 to 17-19 to get Vander Esch? Yes. I agree with you. That move would have given them a presence at ILB'er. But they didn't ... and ILB'er remained a black hole of suck last season.
Should they have simply said, "Ahh, @#$% it" and waited for the 2020 draft? Yeah, no.
Finally, you ask about trading the 2nd round pick to move up every draft. Every draft? No. Some drafts? Damn straight. Would you prefer having Artie Burnt and another pick, or Wiliam Jackson and one less pick? Bud Dupree and a 2nd rounder who turned out to be Senquez Golson, or Vic Beasley and no Golson?
So deal a 2nd rounder to move up 10 spots every draft? No. Deal a 2nd rounder to move out of the 20's and get a player with elite physical tools, a good pedigree, to improve a position desperately in need of upgrade? Yes.