I came across this while doing some draft research.  

https://thedraftnetwork.com/articles/david-montgomery-contract-chicago-bears

I've already said I'm in favor or re-signing him and keeping him around while Fields' develops.  However, as in that article, there is a good argument to be made about how difficult it can be to get value out of a RB on an expensive 2nd contract.   With that in mind IF your decision as GM is to...

1) Let him ride out his existing deal (play next year) and then let him go seeking a potential comp pick in exchange

2) Herbert is good enough to your starter

.... should we trade Montgomery this offseason?  

A good RB averaging over 4ypc who can catch with a cap hit of just $1.2mil should be attractive to teams in need of a RB.  I think we could get as high as a 2nd Rd pick in exchange.  If you are a playoff caliber team in need of a good RB do you prefer the 2nd Rd rookie or Montgomery to help you achieve your Superbowl aspirations?  I don't think I do the deal for a 3rd Rd pick because we have the same benefit of his $1.2mil cap hit next year. 

Again, I lean toward building as strong a running game as possible to help Fields' next year.  For me that's the 1-2 combo of Monty/Herbert.  OTOH if someone offered me a 2nd Rd pick for Montgomery I'd have to take it because I think it makes the overall team better.  Having two 2nd Rd picks makes things look dramatically better in terms of filling needs this offseason.      

With Fields on his rookie deal, you can lock someone like Monty up easier. To me I am leaning towards extending him as long as he doesn't want top money. If he wants that you let him walk. If he is willing to take only top 10 money, I think they have the money for that. Especially once some of these bigger deals fall off after 2022.

If a 2nd rounder can be obtained, I'd do it.  You may not net a better RB room immediately, but you end up better because you've raised the talent at a greater rate than you've lost.  Even if it's a 3rd and 5th, I'm in.

9 hours ago, Mongo3451 said:

If a 2nd rounder can be obtained, I'd do it.  You may not net a better RB room immediately, but you end up better because you've raised the talent at a greater rate than you've lost.  Even if it's a 3rd and 5th, I'm in.

Trade is the only viable option other than resigning him because if you just let him walk, there is no guarantee of compensation. 

10 hours ago, adam said:

Trade is the only viable option other than resigning him because if you just let him walk, there is no guarantee of compensation. 

True.