Yes. there is anecdotal proof. I just provided a screenshot from an Athletic article in my response to another poster. Of course, teams have their own valuation systems that they primarily rely on, but this really isn't that much different. They use it more to "check their work", as the article states.
You're right the Jays wouldn't accept that deal, but that's because they would want younger (and cheaper) talent. The values aren't static, they go up and down based on production, age, control, etc. For example, Corbin Burnes' median value at the beginning of the year was around 130, but it has now gone down to 78.3 due to the expiration of another year of team control.
Yeah, not sure where the poster got the idea that Jansen slowed down. He was pretty consistent throughout the season, and had his best month in September/October.