Magnarella was recruited into talent management in 1990 by manager Bob Cavallo  under the firm Atlas/Third Rail Management. Magnarella and Atlas/Third Rail managed Weezer beginning in 1994. The song "Lisa", written by Rivers Cuomo in 1995, is about Cavallo's daughter, and Magnarella himself is referenced by name in the lyrics ("What's that? She wants for me to do something for Magna"). Magnarella also managed the Rentals, the band started by Matt Sharp, throughout the band's first two albums. In 2001, immediately following the release of The Green Album, Weezer fired Atlas/Third Rail Management and Magnarella. Magnarella later sued , leading to a protracted legal battle. According to Karl Koch, the firing was a "statement of intent" and Rivers Cuomo felt that the band didn't need management, and could simply fund their next album with their own money and pay themselves back when the album sold.