Here's a quick way to figure it.
1) So-called "sharp money" is less concerned with the better team or the "right side" (there is no such thing), than with obtaining value. Value is best defined as the difference between what their line says the game should be and what the actual betting line is.
2) Because they are more concerned with value, they prefer underdogs, as well as specific key numbers, primarily 3 and 7.
3) Seeing the line open at San Francisco -1' means nothing to us, especially with two weeks to go before kickoff. No sharp is going to take Kansas City +1', except on a teaser. They'll wait and see if they can get 3. Nor will they lay -1', when the line might move to PK.
So when the line moves to San Francisco -2, that's your tell that public money is on San Francisco.
4) By the middle of this week it became clear that the line isn't moving past 2, so that's when the "sharp money" bought into it, in some cases buying a point up to +3. Thus, we see the line adjusting back to -1'.
5) Any sharp money holding out for PK will come in late, like today, so you might see another slight adjustment to the line.
Having said all that, I think it's a much better use of one's time to rely on their own handicapping and not pay so much attention to where the "sharp" or public money is going.
I'm on KC myself, along with some props.