In 2006, his UC Irvine head coach, Dave Serrano, retained Wallis as an undergraduate assistant coach. He was promoted to director of operations in 2007 and was part of a staff that reached the program's first College World Series.[2]
Wallis moved with Serrano to Cal State Fullerton in 2008, serving as an assistant coach. The Titans qualified for the NCAA Tournament in all three seasons Wallis was on staff, highlighted by a College World Series trip in 2009.
Wallis again followed Serrano to his next stop at Tennessee in 2011, spending three seasons as an assistant coach with the program.[3]
In 2014, Andy Stankiewicz hired Wallis as an assistant coach at Grand Canyon for the program's first season back at the Division I level.[4] Wallis was promoted to recruiting coordinator in 2016.[5]
Following the 2022 season, Bill Mosiello was hired as the new head coach at Ohio State and hired Wallis as his lead assistant and recruiting coordinator.[6]
Stankiewicz departed Grand Canyon for USC on July 3, 2022,[7] and Wallis was hired as Grand Canyon's head coach five days later.[1] Several coveted GCU players who had entered the transfer portal — including shortstop Jacob Wilson who was playing with USA Baseball's Collegiate National Team and 2022 Western Athletic Conference Pitcher of the Year Daniel Avitia — announced their return to GCU within days of Wallis' hiring.[8]
In his first season as head coach, Wallis led Grand Canyon to its third consecutive WAC regular-season championship[9] and was named the WAC Coach of the Year.[10] He repeated both of these feats in his second season in 2024 in addition to winning the program's first D-I NCAA tournament game and advancing to the program's first regional final.[11][12]
National champion
Postseason invitational champion
Conference regular season champion
Conference regular season and conference tournament champion
Division regular season champion
Division regular season and conference tournament champion
Conference tournament champion