“The past two seasons we have seen so-called big teams in South Africa made to look ordinary by smaller teams," Mangena said on Daily Sun.
Chiefs are under the mentorship of coach Steve Komphela, who was appointed prior to the 2015/16 season and he is yet to guide Amakhosi to a major trophy.
Their rivals, Pirates, are under the guidance of Kjell Jonevret, who was appointed last February.
The Swedish tactician is the third man to coach Bucs this season. Muhsin Ertugral resigned last November and Augusto Palacios took over as a caretaker coach.
"This is because football is evolving. So-called smaller teams are adapting to those changes," he added.
"But the biggest problem for Chiefs and Pirates is that they don’t hang on to coaches for long periods,” Mangena stressed.
“Wits and Sundowns have won recent league titles because of their coaches. Pitso Mosimane has been at Sundowns for about six years now. The same goes to Gavin Hunt at Wits.
“These teams are now enjoying the benefits of investing and trusting their coaches. I think it has made the difference between being successful or not," he concluded.