[SF_Cardinal_Fan]

while they may not be drawing lots of fans in seats both the Rams and Charger franchises are worth a lot more than before they moved

Forbes estimates

Rams 2017 - $3 billion
Rams 2015 - $1.45 billion

Chargers 2017 - $2.275 billion
Chargers 2015 $1.525 billion

https://www.forbes.com/nfl-valuations/list/#tab:overall

https://www.forbes.com/pictures/ghik45ek...9ddd5265a5

I think the prices for pro sports franchises is mostly about comparable sales.
It's a small niche market of billionaire buyers competing to buy a small number of NFL, MLB, or NBA teams. These potential buyers don't seem to focus much on a team's w/l record, home facility, current revenue streams, or any of the other criteria which Forbes uses to assign valuations to teams.
My opinion is that the Chargers and Raiders might be worth more (to a potential buyer) in their home markets of San Diego and Oakland. Specifically, the Chargers went from their own city and stadium to sharing a stadium with the Rams. It's possible that a potential buyer would prefer to buy  a team with it's own identity (San Diego) rather than a team obligated to share a stadium. And the Raiders have a proven fan base in Nor Cal, which a potential buyer might prefer  to the unknown of the Las Vegas market.
Forbes claims the 49ers value "skyrocketed" following their move to Santa Clara.  I think it's possible that Levis Stadium may prove to be a white elephant which a potential buyer of the team would not wish to inherit.

[SF_Cardinal_Fan]

while they may not be drawing lots of fans in seats both the Rams and Charger franchises are worth a lot more than before they moved

Forbes estimates

Rams 2017 - $3 billion
Rams 2015 - $1.45 billion

Chargers 2017 - $2.275 billion
Chargers 2015 $1.525 billion

https://www.forbes.com/nfl-valuations/list/#tab:overall

https://www.forbes.com/pictures/ghik45ek...9ddd5265a5

I think the prices for pro sports franchises is mostly about comparable sales.
It's a small niche market of billionaire buyers competing to buy a small number of NFL, MLB, or NBA teams. These potential buyers don't seem to focus much on a team's w/l record, home facility, current revenue streams, or any of the other criteria which Forbes uses to assign valuations to teams.
My opinion is that the Chargers and Raiders might be worth more (to a potential buyer) in their home markets of San Diego and Oakland. Specifically, the Chargers went from their own city and stadium to sharing a stadium with the Rams. It's possible that a potential buyer would prefer to buy  a team with it's own identity (San Diego) rather than a team obligated to share a stadium. And the Raiders have a proven fan base in Nor Cal, which a potential buyer might prefer  to the unknown of the Las Vegas market.
Forbes claims the 49ers value "skyrocketed" following their move to Santa Clara.  I think it's possible that Levis Stadium may prove to be a white elephant which a potential buyer of the team would not wish to inherit.