He played high school baseball at Villa Park High School and graduated in 2004.
Trumbo was selected by the Anaheim Angels in the 18th round (533rd overall) of the 2004 Major League Baseball Draft. He was promoted to the major leagues as part of September callups on September 7, 2010. He made his major league debut on September 11, 2010 as a pinch hitter for Mike Napoli and then remained in the game to play first base.
With the absence of first baseman Kendrys Morales, Trumbo entered the 2011 season looking for some early-season playing time at first base after an excellent spring in which he displayed his prodigious power. Trumbo hit his first career home run on April 12, 2011, off Fausto Carmona of the Indians. As of September 9th, 2011 he leads all major league rookies with 26 home runs and 80 RBI's. Although he planned to be a stopgap until Morales' tentative return from injury, he is now looking at being the Angels' full time first baseman for the 2011 season due to Morales' season-ending surgery.