Costello has a smooth easy delivery and threw with poise and accuracy. He has a strong arm and is already solid mechanically. He made big throws down the field and fit some balls in very tight windows throughout the tournament.
"Stanford was unreal," Costello said. "This was my first time visiting the campus before and I really liked it there. They have an amazing campus, great coaches and it was a great experience. They pulled me up with the top group and told me they want me to come back next year and will be watching me this season.
"USC was a lot different. It was real fast paced and there were more athletes there. My mom went to USC so I grew up a big fan of the school. I've been going to USC games my whole life and really like it there so I had a great experience at both of these schools."
Costello said he's planning to take his time with the process and is still open to all schools.
"I wish I had time to do more camps and see more places," Costello said. "I would have loved to visit UCLA and Cal in-state and do some out of state visits as well. Next year, that's my goal, I want to go see some more schools and see some new campuses.
"This is a business decision for me and I'm wide open to everyone. USC may be the school I grew up rooting for but honestly, I'm going to give every school a fair shot. I still have three more years since I'm just a sophomore right now anyway so I'm not in any hurry to make a decision."