These stats that appear when you click on any unit are the stats for the general in command of it.

Only the general with the provincial title will influence the income of a province. Other troops stationed there won't influence directly your income. They can influence directly because they raise loyalty, and the bigger the loyalty, the more you can tax the population. But the acumen stat for any general stationed there won't influence anything if they are not in possess of the provincial title.

Your king's acumen stat also influences each one of the provinces you own.