"I was pretty prepared for that and expected it," said Muller. "Brendan was great. We talked about it the whole time. We talked through the decision a lot. In the end, I think it was an easy decision although he struggled with it for a while. I'm really happy for him to go down there with his brother. It's pretty cool."
Muller said he hopes to have Mullins' replacement named in the next month. The ISU coach is used to the process of finding a new assistant, having gone through it every offseason in his seven years.
Jefferson came to ISU last spring from Lake Land College in Mattoon. He got off to a good start before slumping. Jefferson didn't play at Evansville before breaking his collarbone in practice. He missed 10 games before returning for the regular-season finale at SIU and ISU's two games in the MVC Tournament.
"With Ike there's a window still open that he can come back if he wants to," said Muller. "I assume he finds a fit he really likes and does that."
The loss of two wing players doesn't necessarily mean ISU needs to add immediate help there, said Muller.
Zach Copeland, the top returner scorer (9.3 ppg), returns on the wing along with Chastain, while Dedric Boyd and Jaycee Hillsman sat out as transfers last season.
Muller wants to add a veteran point guard to join incoming freshman DJ Horne, allowing Copeland to stay at his natural off-guard spot and not have to play the point as he did this past season.
"I really like where we're at, at all of our positions," said Muller. "I think there will be a lot of competition and depth at each spot, and I think DJ is going to be a really good player for us coming in. I think he'll be able to contribute right away as much as we need him to."
ISU had a campus visit in late March from Derrick Cook, a 6-4 point guard from Georgia Highlands College who averaged 13.7 points, 6.6 rebounds and 4.0 assists. He played Division I as a freshman at Northeastern.
"We're still looking for a point guard. The other two would be the best players we can find," said Muller. "The option would be for a sit-out guy (as a transfer), but we have some flexibility in those."
The Redbirds are targeting Chicago Simeon's Antonio Reeves, a 6-3 shooting guard who averaged 21.7 points for the Wolverines this season. Reeves also visited campus last month.
ISU's returning players began individual workouts last week. Muller said Taylor Bruninga, a sophomore forward who missed the season with a foot injury, is now in a soft boot in his recovery from surgery.
Muller doesn't anticipate Bruninga being able to play during the Redbirds' trip in August to Italy.
"But if he's really good to go and the doctor completely clears him, I would love for it to happen," said Muller. "But we're going to be as cautious as we need to be. If he could play it would help."
Contact Jim Benson at (309) 820-3404. Follow him on Twitter: @Pg_Benson