Stepan, Christian Dvorak and Richardson are expected to be Arizona's other three centers, but rookie Dylan Strome, the No. 3 pick in the 2015 NHL Draft, could take one of those spots.
Strome had 53 points (22 goals, 31 assists) in 50 games with Tucson of the American Hockey League last season and had eight points (three goals, five assists) in the Coyotes' last 10 games.
"He turned the corner last year and I want to see him get away from the corner now," Tocchet said. "I want to see him get a straightaway and separate himself."
Arizona was third in the NHL with 106 goals allowed from Jan. 1 to the end of last season. A lot of that had to do with Raanta, who led the NHL with a .942 save percentage and 1.84 goals-against average (among goalies with at least 20 games) in that stretch.
"He took it to a different level," Tocchet said. "We've got some solid goaltending. You have to have it or you've got no chance."