The 39-year-old Cassar was formally introduced as the third head coach in franchise history Thursday afternoon.
"This is an opportunity of a lifetime," said Cassar, who takes over for Jason Kreis, who left for New York City last week. "I don't think it's quite set in for me just yet. But every time I think about it, I really start to cry."
After seven years as an assistant coach under Kreis, it's understandable why Cassar would get emotional taking over the team he loves so much.
"It means the world to me," Cassar said. "To lead this group of men in particular, that's very humbling. I'm honored."
"We're really excited to keep this within the family," said general manager Garth Lagerwey. "It's as easy a transition as you can possibly hope for because there is no transition."
Cassar has never been a head coach before, but he was instrumental in developing the young talent on the team, spending a lot of his time with the U-16 squad. Plus, he learned under one of the best in the business in Kreis as his top assistant the last three seasons.
"I've learned so much from Jason," he said. "Whether it's from a coaching aspect or from being a leader. But I'm my own person, and I have my own ways."
What is the biggest difference between Cassar and Kreis?
"Jeff cannot shoot lightning bolts from his eyes," Lagerwey joked. "That would be one difference. I mean, if you meet Jeff, he's a charming personality and I think he's going to come across as likable to most folks."
RSL's players like the choice. Nearly everyone expressed their approval over the hiring.
"We got pure positives," said owner Dell Loy Hansen. "I think that's a testament to Jeff that he built a lot of friends, and a lot of people believe in him. When the locker room virtually comes to ownership and says, 'this is who we're comfortable with,' you know you've got a good fish on the hook."
It does make it easier that Cassar takes over an extremely talented team that was one penalty kick away from winning the MLS Cup. But, it may take a while for Cassar to put his own stamp on the team.
"One of the things Jeff is going to have to do is establish leadership in the locker room," Lagerwey said. "I think Jeff is going to have some bumps in the road along the way. It's not going to seamless. It's not going to be without any hurdles. But that's OK. That's how you learn."
"I'm just really passionate about this team," Cassar said. "And I feel that I was the right man for this job."