I don't think so. I think most of the good ones will be gone by round 3.
This has been a common theme, as people see 4th rounders doing well. Thing is, for an accurate assessment, you'd have to look at the ones who didn't make it also, and mostly no one is doing that.
The huge majority of 4th round and later RBs aren't very good. That's where you get STers and guys who lack burst/speed/power/ or something else.
How many RBs can you name taken in the 4th or later how are good? Ekeler, there's one. Pacheco in the 7th. Most good RBs are taken in rounds 1 and 2.