Okay, here's my take on each of the 3 scenarios.
Scenario 1 is self explanatory.
The Browns would have the ball 1st and 10 from their own 40 with roughly 4:00 to go.
So clearly this is the preferred outcome, but in my opinion the low probability of conversion and consequence of not converting is too great, when looking at the other scenarios.
Scenario 2 has the following realistic outcomes (all clock times and yardages are approximate)
-Chiefs take over at the CLE 32, get 0 first downs and then kick a 45-yard FG to go up 8 with 3:00 to go. Browns get possession back down 8 on their own 25 after a kickoff touchback.
-Chiefs take over at the CLE 32 and get 0 first downs and then miss a 45-yard FG. Browns get possession back down 5 on their own 35 with 3:00 to go
-Chiefs take over at the CLE 32 and fail to convert a 4th down after 0 first downs, Browns get possession back down 5 on their own 25 with 3:00 to go.
-Chiefs take over at the CLE 32 and get 1 first down and then kick a 35-yard FG to go up 8 with 1:10 to go. Browns get possession back down 8 on their own 25 after a kickoff touchback.
-Chiefs take over at the CLE 32 and get 1 first down and then miss a 35 yard FG. Browns get possession back down 5 on their own 25 with 1:10 to go.
-Chiefs take over at the CLE 32 and fail to convert a 4th down after 1 first down, Browns get possession back down 5 on their own 15 with 1:10 to go
-Chiefs take over at the CLE 32 and run the clock out with 2 first downs or a touchdown. Browns never get possession back or get it back down 2 scores effectively ending the game.
I re-ordered your outcomes for clarity, so the 0 first downs and 1 first down outcomes are grouped together.
If the Chiefs have not secured the first 1st down, depending on the time remaining in the game and remaining yardage, they could attempt a FG if they believed they couldn't convert on 4th down. Kicking a FG could be smart there depending on the exact circumstances and how confident they were in their kicker, (who had missed a couple already).
If the Chiefs did secure an additional 1st down, they would be at the CLE 22 (at least) and look at ending the game. From that field position I believe they would go for it no matter what, completely taking the FG off the table. Because with a little over a minute remaining, the reward of 4th down conversion far outweighs the risk of failing, because with that clock and field position, the higher difficulty task for the Browns offense would be scoring a touchdown at all, not getting the 2PT conversion.
Scenario 3 takes a KC FGA off the table. They took over on their own 28 with 4:09 to go (all clock times and yardages are approximate)
-Chiefs do not convert a first down and punt the ball back to the Browns from their own 35 with 2:50 to go. Browns get possession back down 5 from their own 20.
-Chiefs do not convert a first down and fail to convert a 4th down from their own 35. I firmly believe they would NOT have attempted this since a conversation would not have ended the game and risk of a failed conversion was too great, but for arguments sake we'll put it as an outcome. Browns get possession back down 5 from the KC 35 with 3:00 to go.
-Chiefs convert 1 first down, and then punt on their second set of downs from their own 45 with 1:25 to go. Browns get possession back down 5 with 1:10 to go from their own 10.
-Chiefs convert 1 first down and fail to convert a 4th down from their own 45. As aggressive as Reid is, I do believe he would have gone for it on 4th and 4+. Browns get possession back down 5 from KC 45 with 1:20 to go.
-Chiefs convert two first downs and end the game. Browns never get possession back.
I agree with you here that if the Chiefs don't convert a 1st down, they would punt. So we can take the go for it scenario off the table there.
If they do convert a 1st down, they would most likely be fine either way by punting or going for it, and the time and yards remaining would be the biggest factors here in what they decide.
So having gone through these, we can basically map each outcome 1:1 for each scenario and evaluate that way in the decision to punt or not punt. I'll put the non-punting outcome on the left side and punting outcome on the right. Because of the variance in punting distance and kick returns, any scenario that's within 5 yards of the one being compared we'll call even. Any outcome that's significantly better when compared head-to-head i'll color green.
Chiefs not securing a 1st down and making a FG VS. Chiefs not securing a 1st down and punting
Browns would have to score 8 points at their own 25 vs. having to score 7 points at their own 20 with approximately 3:00 remaining.
This one is mostly even, but having to convert the 2pt conversion here should give a slight edge to the punting scenario.
Chiefs not securing a 1st down and failing to convert on 4th down VS. Chiefs not securing a 1st down and punting
Browns would have to score 7 points at their own 25 vs. having to score 7 points at their own 20 with approximately 3:00 remaining.
Mostly even, slight edge non-punting.
Chiefs not securing a 1st down and missing the FG VS. Chiefs not securing a 1st down and punting
Browns would have to score 7 points at their own 35 vs. having to score 7 points at their own 20 with approximately 3:00 remaining.
This one the advantage goes to non-punting. However I strongly believe that Reid would only kick the FG if he believed the probability of making the kick was much higher than the probability of converting a 4th down, making that outcome fall on the less likely scale.
Chiefs convert a 1st down and fail to convert on their second 4th down VS. Chiefs convert a 1st down and punt on their second set of downs
Browns would have to score 7 points at their own 15 vs. having to score 7 points at their own 10 with approximately 1:15 remaining
Mostly even, slight edge non-punting.
Chiefs convert a 1st down and fail to convert on their second 4th down VS. Chiefs convert a 1st down and fail to convert on their second 4th down
Browns would have to score 7 points at their own 15 vs.
having to score 7 points at KC 45 with approximately 1:15 remaining
This one the advantage goes to the punting scenario.
Chiefs convert two 1st downs VS. Chiefs convert two 1st downs
Browns lose
So of all the realistic outcomes, we can see that 4 end up even, 1 outcome advantage non-punting, and 1 outcome advantage in punting. But for the full totality of evaluation, we should also include outcomes that are only available in one particular scenario:
Browns convert 4th and 9 VS. N/A
Drive continues vs. Drive ends
Chiefs score touchdown VS. N/A
Browns lose vs.
N/A
So here we have one more advantage that favors non-punting, and one more that advantage that favors punting. But as we previously discussed, the odds of 4th and 9 conversion are low, and the Chiefs scoring a TD possibility should be taken seriously...because that is an outcome that can happen with non-punting regardless of 0 or 1 prior first down conversions, so it's always a threat.
I think that additional outcome of an instant loss is reason enough to punt, but even if you think that it's close enough to be even, and if the outcomes are even you should err on the side of going for it, the decision then should be based on how much you believe in your defense.
If you believe your defense won't surrender any first downs, you should go for it.
If you believe your defense will surrender one first down but not two, you should punt.
If you believe your defense will surrender two first downs, you're going to lose either way.
Punting is the better move if you are not confident in having a stalwart defense, because you have more wiggle-room. Going for it is better the more confident you are in your defense, and especially if the other team's kicker isn't good.
The other reason to go for it is if you believe your defense is
so bad that it can't stop the other team from getting two first downs
or a touchdown. This option is basically a hail mary because you're banking your entire season on the success of the 4th and 9 play. I don't believe we were in a hail mary situation with 4:19 left in the game, so I was fine with punting.