Give a stream of consciousness and then the final answer. A lightly regarded prospect coming out of college, Brady was selected by the New England Patriots with the 199th overall pick in the sixth round of 2000 NFL Draft and has since spent his entire 18-season career with the Patriots. Since Brady became their starting quarterback in 2001, the Patriots have never had a losing season and have won 14 division titles. The Patriots played in twelve AFC Championship Games from 2001 to 2017 -- including seven in a row from 2011 to 2017 -- and won eight of them. Brady and Patriots head coach Bill Belichick have combined to form the most successful quarterback-head coach tandem in NFL history, winning more regular season games and postseason games than any other such duo as well as appearing in eight Super Bowls. All of these events set new NFL records.

Based on this passage, when did tom brady become a starter for the patriots?
To answer this question, we should know that: Since Brady became their starting quarterback in 2001, the Patriots have never had a losing season and have won 14 division titles.
So, the final answer is 2001.