That's why term limits for U.S. Senators are pretty useless. A lot of these Senators are heavily reliant on their aides, that would not be term limited. They are simply passed around to Senators in their party. They research, they write laws, they broker deals... Term limit aides as well? That would be worth some consideration.
certainly some Senators pull their own weight, but so many don't while their aides pull the strings.
Ex. My Senator, Osama Lovin' Patty, is nothing but a puppet for Hillary, the DNC and her aides.
You've hit on the very reason I'm against term limits. It gives more power to the staff and behind-the-scenes people who we often don't know and don't elect. I'd rather have the power remain in the hands of the people we can re-elect or not every few years.