Different managers will draw that line differently according to their own thoughts on how important it is to avoid a relegation playoff. As I mentioned, the money issue isn't really an advantage since the final place int he standing has a small influence on attendance the following season that makes the playoff income advantage really a wash. We all know the draft advantage isn't so valuable given what the prevailing opinion on the draft is these days (read other threads for those complaints...). For me personally, that extra training game is probably the tipping point since I know from my experience this season, the first time I was truly on the cusp between 5th and 6th place, that I really was undecided on whether or not to throw games so I could finish in 6th, and wanting to get that little bit of extra training would have pushed me to just go for 5th. (In the end, I halfheartedly decided to go for 6th even though I hate losing, but failed and finished 5th.)
Don't ask what sort of Chunks they are, you probably don't want to know. Blowing Chunks since Season 4!