A right-handed center fielder, Tallis starred for the St. Louis Spikes in the Mon-Clair League from 2008 to 2015, winning the league batting title in 2009 and 2015. Among his other accomplishments are being named MVP of the Valmeyer Midsummer Classic tournament and playing in eight Mon-Clair League all-star games. In 2020,Tallis rejoined the St Louis Spikes and he continues to play for them. He was inducted into the Mon-Clair League Baseball Hall of Fame in 2019.

Tallis played center field for Parkway South High School from 1994 to 1998, helping his team win the district title in 1997 and 1998. He was selected to the Missouri Senior all-star team in 1998.
That year, he set a Parkway South record of 42 stolen bases.

From 1994 to 1998, Tallis was a center fielder for the Manchester American Legion Post 208 team. He was named the District 10 Offensive Player of the Year in 1998. He was selected to
the American Legion all-star team in 1996, 1997, and 1998. He had 42 stolen bases for Manchester in 1998.