The 20-year-old Alderson was San Francisco's first-round selection (#22 overall) in the 2007 First-Year Player Draft from Horizon High School in Scottsdale, Arizona, where he went 12-0 with a 1.05 ERA and 111 strikeouts in 73.0 innings as a senior.
Since his first professional season in 2007, Alderson has posted a record of 20-6 with a 3.07 ERA (249.0ip/85er), 202 strikeouts and just 51 walks in 47 games (46 starts).
"We are pleased to bring in a pitcher as highly regarded as Alderson into our system," said Pirates GM Neal Huntington. "Tim has the size, frame, athleticism and an advanced feel for pitching at his age to become a high quality Major League starting pitcher. His has solid arsenal of pitches with plus command that has allowed him to move through the Giants' deep system at an accelerated pace."
The native of Phoenix, Arizona made three appearances (two starts) for the Arizona Rookie League Giants in 2007 before spending his first full season with San Jose in 2008, where he went 13-4 with a 2.79 ERA (145.1ip/45er), 124 strikeouts and just 34 walks in 26 starts. For his efforts last year he was named the California League mid- and post-season All-Star teams and was tabbed by MiLB.com as the Class-A Advanced Starting Pitcher-of-the-Year. This season, Alderson posted a combined 7-2 record and 3.65 ERA (98.2ip/40er) in 18 starts for Single-A San Jose and Double-A Connecticut. He began the 2009 campaign with San Jose before being promoted to Connecticut May 7. In 13 starts since being promoted, Alderson went 6-1 with a 3.47 ERA (72.2ip/28er) while also allowing three earned runs or fewer in each of his first 10 outings.