Senior professor need to help by picking up more of the administrative and service loads. I am not saying young faculty should not get involved, they sh ould. I get calls from people who ask my newer faculty to help out with their committees. Instead, I usually recommends some mid-career people who have established scholarship and would probably be a lot better for the p articular committees. At times however, I will help young faculty by recommending that they serve on certain committees w here they can gain visibility, learn how the college functions, and make connections.
Chairs can help in other ways with respect to workload.
Take, for example, teaching assignments. I am expected to have my faculty average 17 students per class, four classes per semester. However, if a professor t eaches three classes, two with 17 students, and the third with 35 students, the commitment can be considered equivalent to four classes of 17 students per class. Or, if the number of students taught by a faculty member in one semester is very high, as ch air I can give the faculty member released time the next semester. I use this system to give young faculty teaching assignments requiring fewer preparations, or to allow them to borrow ahead to get started on research.