Hall of Famer and fellow Level of Excellence inductee Roy Halladay joins Key at the top of the all-time rotation of pitchers who were never teammates. His Blue Jays career spanned 12 seasons from 1998 through 2009, where he accumulated a bWAR of 48.4 and fWAR of 48.7 by posting a 148-76 record with a 3.43 ERA and 3.47 FIP over 2046.2 innings. He also pitched 49 complete games with 15 shutouts.
He was a six-time All-Star as a Jay, led the AL in innings pitched three times, and won the 2003 AL Cy Young award after posting a 22-7 record with a 3.25 ERA, with nine complete games in 36 starts and 266.0 innings. His 8.1 bWAR that season is tied for third all-time with Roger Clemens for a single-season WAR for Blue Jay pitchers.
Unfortunately Toronto never made the postseason during his tenure, but he did go on to find postseason success with the Phillies in 2010-2011. In fact, he won the 2010 NL Cy Young in his first year with Philadelphia, when they lost in the NLCS to the eventual World Series champion San Francisco Giants that year. He tossed the 20th perfect game in MLB history on May 29th against the Marlins, and went on to pitch a no-hitter in Game 1 of the 2010 NLDS against the Reds.