They can take a RB in rounds 2-4 and get the same production. Maybe better.
Chuba was a 4th round pick. Breece Hall was a 2nd, James Connor was a 3rd, Jordan Mason was undrafted. Kamara was a 3rd round pick. Etc etc etc.
Najee will be 27.5 by the time next season kicks in. Way more important to put money and picks into O-line and WR, even D-line.
But you're not putting both money and picks in. You're putting one or the other in, and using the other to cover the other things.
So the question for me is whether you'd have a 2nd/3rd round RB and Mike Williams, or a 2nd/3rd round WR and Najee Harris? Because Williams is getting paid more than Harris is projected to next year. You can repeat the exercise over other positions. Harris or Ogunjobi? For me, albeit with a bit of nerves about Harris' age and how long it's taken him to come really good, that's Harris.
If they can be patient and find a Tyler Allgeier in the 5th round, where the RB supply is still strong but other positions aren't all that, then cool. But I have my doubts about them doing that when the RB is going to be pivotal for them.