Expected value of making 3rd/4th (as opposed to 5th)
You negate the fact that "tanking" for 5th spot usually lowers your this seasons income. Seldom teams end up at the 5th with noone else wanting it. We know that good record overall and winning away games, gives you a pretty big bonus, over teams who opt to lose. Well I have never ended up 5th. But I have experience of being the last a few seasons ago. My arena income was constantly dropping. II.div was a disaster considering arena income, although I finished with 22-0 record. This season my arena income has been rising, but not having the same amount of season ticket holders, I still can't match the first incomes I had when promoting the last time. So if getting a better spot in standings adds more STH-s. I would opt for the best spot I can reach, instead of losing about 50k a week (and more adding up over the season) to tank for 5th, to maximize the STH thus increasing income max and "salary cap" leverage.
There are a lot of different teams out there, some still sell players before playoffs (even if they make it), for the "higher transfer value". So shooting out some plain averages is not really acceptable research.