First in the minds of many portfolio managers is current income or yield.
Performance is measured by the book yield on the portfolio at any given time.
The stream of income from coupon cash flows is critical to healthy margins. Total return takes into consideration such things as reinvestment of interest payments and the appreciation or depreciation of the bond's price as the market moves up and down. Moreover, savvy portfolio managers realize that relatively good book yields today may become mediocre tomorrow if rates rise. Therefore it makes sense to manage things like reinvestment of cash flows and changes in market value as well. I recommend a rule of thumb about how much risk to accept in terms of cash flow volatility and market value fluctuation.