That came to an end Friday, when he suffered a loss to his childhood rival, Clayton Kershaw, and the Los Angeles Dodgers in a rematch between the two pitchers.
Since 1998, Los Angeles Angels of Anaheim pitcher Jered Weaver and former Dodgers pitcher Kazuhisa Ishii are the only pitchers to have begun their careers 5-0.
Anderson struggled with control Friday, walking four while allowing four hits, but managed to evade a lot of other would-be damage by limiting the Dodgers to just a two-run home run in five frames of work.
But his opponent, a two-time Cy Young winner, outdid him, allowing just one run over 7.0 innings pitched.
Anderson is now 5-1 with a 3.21 ERA on the season.
When he last faced Kershaw and the Dodgers, his team supported him with 18 runs of support. Though accruing 13 hits and a pair of walks Friday, they struggled to plate baserunners in the 4-3 loss.