Štombergas is one of the greatest Lithuanian basketball players of all time, and he was also considered to be a great team leader, as he managed to play very well under pressure, and at the end of games.

Štombergas' club teams during his playing career, were, in the order in which he played for them: Atletas Kaunas, Vostok Shanghai (Chinese CBA), Žalgiris Kaunas, Kinder Bologna, TAU Cerámica Vitoria, Efes Pilsen Istanbul, Unics Kazan, and Ülker Istanbul.

He holds the record in the EuroLeague, since the year 2000, for the most 3-point field goals made in a game, without a miss.

Štombergas played for the senior men's Lithuanian national basketball team, from 1995 to 2004.

He briefly served as head coach in the 2013-2014 season, before resigning in April after disappointing results.